Well, you can't relist directly through Auctiva. You can send a listing to eBay for a second time but eBay has no way to know that it's actually a relist.
And relisting through eBay is fine. You can edit your listing in their description field OR edit the original listing here and use the "Get HTML" button to plug the code into the description box on eBay's relist page.
Does that help?