Refreshing Web User Control

I have a web user control named shopcart which is nested in the master page.
Then i have catalog CONTENT PAGE which is using the same master page.


When i add an item to the shopping cart it does not reflect the small shoppingcart immediately.


Rather, when i go to another page of click the refresh button the newly added item gets displayed in the shopcart.


The web user control has a method PopulateShopCart in the Load Event Handler but it is not fired when i add new item from the catalog.


How do i make it refreshing immediatelly if i add a new item in the shopcart.


Thanks

...