Yup. It's tough to get the bolt remains out if you've snapped the bolt, but it can be done. It's a lot easier to take it to a machine shop and let them deal with it.
If you've stripped the threads, you'll have to retap it one size bigger and use a larger bolt. You could look into helicoiling it, I don't know if helicoils can take the torque that the head needs, but a machine shop would likely know - and I bet some of the guys on here would too.