Normally, Insertion Fees are non-refundable. However, if your listing ends without a winning buyer or ends with an Unpaid Item (UPI), you may qualify for a credit by relisting the item. If the item sells the second time, eBay will refund the Insertion Fee for relisting.

You must use the official Relist feature in order to receive the Insertion Fee credit. Copying and pasting the content of the original listing into a brand new listing, will not enable eBay to track that you are relisting the item and will prevent you from receiving a credit.

General requirements for the credit

You must relist the item within 90 days of the closing date of the original listing.
Only the first relisting of an item is eligible. Subsequent relistings of the same item do not qualify.
Both the original listing and the relisting must be in Online Auction or Fixed Price format (not Store Inventory format or Real Estate Advertisement).
Both the original listing and the relisting must be single-quantity (not Multiple Item or "Dutch").
The starting price you set for the relisted item must not be greater than that of the original listing.
The relisted item must not have a reserve price if the original listing didn't have one. If it did, the reserve price you set for the relisted item must not be greater than that of the original listing.
The relisted item must end with a winning buyer. If the item doesn't sell the second time, the Insertion Fee is not refunded.
Qualifying Unpaid Items that are relisted and close successfully will receive a standard relist credit automatically if the item is relisted and sells.