Hi shopwithcarolina,
There's actually no way to update the images on the store window, even if you change all the images on eBay...I was unclear about this myself until today.
If there's a listing that's showing the wrong image in the store window, or, for some other reason, you have listings you don't want displayed in the store window, you can make them hidden in your Auctiva store. This can be done at Auctiva -> Store(tab) -> Store Window -> Edit Items. Any items that are made hidden will not be displayed in the Auctiva store or store window the next time it refreshes...it does so every 2 hours.
I hope this helps=)
-Mike