In reply to chmckay:
Had the same problem and got them professionally repaired by Feet First. Friendly to deal with and the work they did was very good. Wasn't cheap (thinking about £120 but can't find a receipt), but was cheaper than new boots.
Looked at DIY options, but couldn't think of anything I'd be confident in. Didn't want to be stuck halfway up a mountain with a boot that's falling apart.