Welcome back!
Due to this quirk, many people wonder how to maximize their opportunity for FastPass use at the Disney World theme parks. When the soonest they can get another FastPass?
Photo by: mrkathika
Well, typically, you can get a new one once your within 2 hours of your initial return time. However, this varies greatly and based on the number of guests at that park, you may have to wait until you have an hour left or even minutes. You pretty much just have to keep trying.
The beauty of the FastPass is that it allows you to visit the non-FastPass rides while you wait for your return time window. Hit those rides that are close to your FastPass ride and get them out of the way while you wait.
Also, big tip, don't rush to get back to the FastPass ride at the first available return time -- you'll only be competing with the other people that get the same return window. This means you may end up waiting in line, anyway. Best to return sometime in the middle of the return time window (you can actually use the FastPass after the window has expired), so you let the people that are returning at the first opportunity work through the ride. Then, you just walk on like a VIP!