Index: image_captcha.module
===================================================================
--- image_captcha.module	(revision 1192)
+++ image_captcha.module	(revision 1279)
@@ -52,6 +52,12 @@
     'access callback' => TRUE,
     'type' => MENU_CALLBACK,
   );
+  // callback for refreshing the image
+  $items['image_captcha/refresh'] = array(
+    'page callback' => 'image_captcha_captcha_refresh',
+    'access callback' => TRUE,
+    'type' => MENU_LOCAL_TASK
+  );
   return $items;
 }
 
@@ -175,7 +181,7 @@
         $img_src = check_url(url("image_captcha/$captcha_sid/". time()));
         $result['form']['captcha_image'] = array(
           '#type' => 'markup',
-          '#value' => '<img src="'. $img_src .'" alt="'. t('Image CAPTCHA') .'" title="'. t('Image CAPTCHA') .'" />',
+          '#value' => '<img id="image-captcha-image" src="'. $img_src .'" align="middle" alt="'. t('Image CAPTCHA') .'" title="'. t('Image CAPTCHA') .'" />' . theme('image_captcha_refresh_link'),
           '#weight' => -2,
         );
         $result['form']['captcha_response'] = array(
@@ -186,9 +192,55 @@
           '#required' => TRUE,
           '#size' => 15,
         );
+
+        $result['image_url'] = $img_src;
+        drupal_add_js(array(
+          'image_captcha' => array(
+            'ajaxUrl' => url('image_captcha/refresh/', array('absolute'=>true)),
+            ),
+          ), 'setting');
+        drupal_add_js('
+          function change_image() {
+            $.get(
+              Drupal.settings.image_captcha.ajaxUrl
+              + $("input[@name=\'captcha_sid\']").val(),
+              function(response) {
+                $("#image-captcha-image").attr("src",response);
+                $("#edit-captcha-response").val("");
+              }
+            );
+            return false;
+          }
+          ', 'inline');
         return $result;
       }
       break;
-
   }
 }
+
+/**
+ * Menu callback function to refresh the CAPTCHA image
+ */
+function image_captcha_captcha_refresh($captcha_sid) {
+  $result = image_captcha_captcha('generate', 'Image', $captcha_sid);
+  echo $result['image_url'];
+  exit;
+}
+
+/**
+ * Hook_theme implementation for CAPTCHA refresh button
+ */
+function image_captcha_theme() {
+  return array(
+    'image_captcha_refresh_link' => array(
+      'arguments' => array(),
+    ),
+  );
+}
+
+/**
+ * Default implementation of theme_image_captcha_refresh
+ */
+function theme_image_captcha_refresh_link() {
+  return '<span id="image-captcha-refresh-link"><a href="javascript:void(0)" onclick= "change_image();return false;" title="Refresh Image">Refresh Image </a></span>';
+}