Please review our full tutorial for how KickSync's bulk relister works.
The important points:
1. The relister will only relist your products that are not sold out. It just keeps your in-stock inventory active on eBay.
2. You should do your relisting at KickSync. If you bulk relist on eBay direct, or from a third party, you may unintentionally relist a product you have already sold on Amazon, as that third party app won't have your Amazon sales information.