Can I reactivate my Peggle Nights in-app purchase on my new iPad without being charged again?

Question

I own Peggle for iPhone and bought the Peggle Nights addon from within the app. I installed Peggle on my new iPad, but Peggle Nights isn't available.

I've seen other iOS games (like 100 Rogues) that have a "check for purchases" feature alongside "purchase", but Peggle doesn't have this. If I click "purchase", will I be charged another $4, or will the app just reactivate my purchase?

(After a few back-and-forth emails with PopCap support trying to get them to understand my question, they punted and suggested I ask Apple.)