Add option to change reload all translations

You have this option by selecting "Translation updates replace existing ones, new ones are added". What you miss however is a way to force the module to reload all translations. But note that this is a crude one and it will reset all locally modified translations.

This could be done more subtle if we have checkboxes for each module/translation and reload the translations for the checked ones. How simple this may seem, it may lead to confusion. Reloading a translation for one module may affect translations throughout the whole site. Many modules translate the word 'Administer' or 'email'. It is l.d.o which integrates translations for all modules and Drupal by design uses one translation for all modules. There is no way around this.

An other approach is an interface to list, edit(?), reset(?) and delete the locally modified translations. Reset (unflag locally modified or flag for reload) and delete only works in combination with reloading the translation.

- my two cents -

Changing title and status accordingly.

These strings are only translated by po file when they are not yet saved by the admin. Once one of these forms is saved, it can no longer be changed by the translation interface or upload module. It is a core mechanism that Localization Update module can not change.

So there is no workaround to reset all the translations of one module? I'm urged to reset User Relationships module translations because my website launch is on Monday :( all the rest have been properly translated by the localization system.

Have a try with this:
* delete all records from the l10n_update_file table. This will clear the history of current translations and will cause l10n_update to re-import all translation files.
* Make sure your have the right setting to not overwrite customized translations.
* Check translations status and import all translations.

Alternative:
* Use the Localization Update Reset sandbox project to delete all existing translations.
* Import translations.

In all cases test first and make backup(s)!!

Thank you, tried the alternative and some of the issues have gone. However some others still show untranslated strings even when they have its translations available.

The bad thing about LUR (the alternative) is that clean the override module strings too.

@warmth, Localization Update Reset should respect the l10n_update override options. When your Update mode is 'Edited translations are kept ...' your customized translations should not be deleted. If you select 'All existing translations are kept ...' LUR will not delete any translations. To see which translations are customized, check the 'l10n_status' field in the 'locales_source' table. Note that strings which are edited (customized) before l10n_update module was enabled are not marked as customized.

I understand but I have my settings set to overwrite existent, is not that enough to wipe everything and start from scratch? or overwrited (after l10n_update module enabled) will be kept no matter what?

Live dangerously ;) make a database backup an have a try.

As I said I already did, some of the overwritten were kept but some others weren't... Hearbeat and Privatemsg modules are half translated to Spanish so I ended with the same issue plus some of the overwritten gone :P

Here is an very easy way reseting all translations and beginning with fresh downloading all contrib translations of the installed modules from http://localize.drupal.org/

First, make a backup of your database.
Put this in a terminal:

drush sql-query "TRUNCATE TABLE l10n_update_file" && drush sql-query "TRUNCATE TABLE locales_target" && drush l10n-update

I made an alias from this in my .bash_aliases, so it will make my life easier for the future. ;)

alias drush-l10n-reset='drush sql-query "TRUNCATE TABLE l10n_update_file" && drush sql-query "TRUNCATE TABLE locales_target" && drush l10n-update' 

The problem is that I don't have Drush installed in my VPS :(

Sorry to hear that.
But this could also be done with phpMyAdmin.
First of all make a backup of your DB.
Then you should export the status quo of your translations and the translations been downloaded, before you do anything else, to an *.po file. In Drupal this could be done in:
http://yoursite/admin/config/regional/translate/export

Back in phpMyAdmin you should delete the content inside the tables l10n_update_file and locales_target.
Do NOT delete the whole tables l10n_update_file and locales_target, but what´s inside, the content in there.
Then you start your localization from the scratch in Drupal. Go to
http://yoursite/admin/config/regional/translate/update
and start downloading it all again.
All made own translations are also deleted, so you have to re translate them.
But you could search in your exported *.po file for them or export the new status of downloaded translations and make an diff over the two *.po files. The *.po files are raw text files, that can be edited by an normal text editor. But they can reach a big file size. My ones are about 2Mb´s.
I hope this helps you a bit.

Great, thanks! I will give this a try next time!

Coming from #1396302: Translations are not updated, and existing translations are lost as I'm experiencing the issue on multiple sites again (D6).

In case others need LUR for D6, here is the correct command to clone a different branch than master:

git clone --branch 6.x-1.x http://git.drupal.org/sandbox/sutharsan/1397740.git localization_update_reset

The helper module still outputs weird messages, e.g.: "Your translation update mode does not allow translations to be deleted. Change this setting before you continue." (linking to ./admin/settings/language/update, but not saying what setting is supposed to be changed), and "Todo ... translations deleted: [Checkbox] Deutsch (15284 translations)". Very confusing, but seems to work.

I'd still favour having the reset functionality in the main module; searching for the helper module again kept me running broken/inconsistent translations for weeks ;)