I thought that if you didn't use your designated FP+ time that you lost it. Well earlier this week we did not use two of our times because we rode Everest early without a wait time and didn't want to walk all the way back over there. Well I was looking at the app later and it let me reschedule the FP for a later time even though it was a few after the time had expired. This may be a glitch but it worked then but I wouldn't trust it very often.
