Hi Tina - What you can do is go ahead and relist, then make your changes to the active listing, which is pretty easy. If you wish to make changes within the template area (description, seller details, pictures, or the template itself), you can copy and paste the HTML from your revised listing in Auctiva to your active listing in eBay as follows:
1) Locate your listing in your Saved Listings folder in Auctiva, open it, make any necessary changes, preview, and save.
2) In your Saved Listings folder, click the <HTML> icon to the right of your listing.
3) Select all of the HTML in the popup box and copy it.
4) Locate the item on eBay and click the "Revise your item" link.
5) Click the "HTML" tab on top of the Description box.
6) Select all of the HTML that's there, paste the copied HTML in its place, and save your changes.
Keep in mind that the HTML copy & paste described above only applies to the template area. If you wish to revise items outside the template (title, category, price, etc.), you need to do that directly from the ebay "revise your listing" page.
In your case, I would make all your changes in Auctiva before relisting, because once you get a bidder, you are restricted in the kind of changes you can make, so you want to be able to transfer your new HTML as soon as you relist.
Hope this helps.