Hi Attilio,
Since the price has not been updated automatically, I assume you have lowered it through eBay's "Revise your Item" form. Please file a support request regarding this issue using the appropriate link on our help page:
http://www.auctiva.com/free_auction_software_help/help.aspx
Our support staff will be able to have your Auctiva store/store window prices manually updated for you.
-Mike