I feel there are places where reboots should ocurr, and places where they shouldn't.
DO:
Reboot continuity based franchises where going forward is almost impossible. Batman and Robin is a good example. If a series is tangled in it's story, or has gathered general apathy from the public, stop, wait a bit, then release. Superman Returns? Reboot please! The franchise was painted into a corner, in my opinion.
Do: Reboot if you want to take the franchise in a different direction. Even if you've only done one film, and it's a completely different direction, then a Reboot is acceptable. However, if you only have one film, don't rush out a reboot quick, like Punisher: War Zone. Wait until the interest rises.
Don't: Reboot a franchise with no continuity. Because that's not a reboot, just another chapter in a series. James Bond is a good examples. It wasn't untill Quantum of Solace that any serious attempts at following a plot from one film to the next popped up. In fact, Bond never even stayed with or mentioned any of the Bond Girls from one film to the next, did he?
Don't: Offer a reboot as the all cure panacea. Yes, Daredevil and Elektra wheren't exactly great, so now there's a reboot. Now, wake me when they confirm it doesn't suck again.
And those are my thought on reboots.