Genie+ gives you the chance to take advantage of so many Disney park hacks, but many people assume that their allowance of three fast passes per day stops there. However, former Disney staffers want you to know that's not the case at all. Although you start your day with three fast passes, you can book even more once you've used them all. You can do this on the app, or in person at a park kiosk!
In fact, there's no real limit to how many fast passes you can use; you just need to remember to use what you have before booking another. And, of course, you won't be able to book anymore if there aren't any available.