If I have to use my brakes I heat manage with my ears. When your brakes start to overheat you'll hear the sound change. At that point I pull over and take a photo break.
It's also possible, if you've got nice thick brake pads, to ride the brakes hard at that point. If you're lucky the surface of the pad will melt and slough off, leaving nice fresh brake pad material. But even though it's possible, I don't recommend it because your tire might blow off first.