Ebay buyer paid after unpaid item case was closed?

[Hannah Lawrence]

I sold an item nearly a month ago now. The buyer did not pay me. I wait more than a week before opening an unpaid item case. Send her an invoice and a private message. I received an echeck from her but it did not clear. I waited another week and sent her another message warning that her check did not clear and that payment was required immediately or I would close the case, block her, and relist the item. I never received a single respose from the buyer. I closed the case and received a message from ebay saying the case was closed, that I'd receive my fees bakc, and that the buyer's account would be noted and she would not be allowed to leave feedback. Great I thought. The next day I relisted the item. Today (3 days after the case was closed) I received an email saying that my buyer paid and I need to ship the item.
I'm looking for advice on how to proceed. I blocked her when I closed the case and don't have a desire to send her the item. Is there a way to deny her payment? I've already got new bidders on the relisted item and don't want to end teh auction.
Any help or suggestions would be greatly appreciated. Thank you!