Your listings will come back, but it does take time. Here's the FAQ:
http://www.auctiva.com/free-auction-software-help/help.aspx#listings-disappear
If you've got a large inventory of Buy-It-Now and want to maintain 30 day (permanent-like retail) listings, you'll need either an ebay Store, or a separate eCommerce solution for sales, which Auctiva might have later in the year.
Danno