Allows you to refresh the data that Prestashop has saved for the affiliates. This allows you to empty the current cache and renew with current data.  The following tutorial explains how to refresh the cache using the PrestaShop 1.5 interface.

How to Clear the Cache for PretaShop 1.5

1. Login to the Administrator as an Administrator
2. Hover over menu bar where it says STATS - click on REFERRERS when it appears at the bottom of the drop-down menu.
3. You will see the following screen:
   
   
   
   
4. Click on the button labeled REFRESH CACHE.   This will clear the data cached for the Affiliates and can be used on a regular basis.

The option to clear the cache is primarily used to refresh the data gathered for the affiliates by PrestaShop 1.5. This allows for newer data to be gathered and to also potentially improve performance if there is new data that can be cached in place of old data that may no longer be necessary.