I recommend making sure to have a current backup before fiddling with the file system. Other than that, GParted should to the trick, like @level_101 said.
I just did a full backup and manually copied important files to my NAS. Worst case I just do a fresh install of Mint and go from there. ;-)
Yeah, it can be annoying to recover but as long as you have the data you care about its just... Annoying. Not a real problem at all.
Sometimes a full re-install is the best way to go anyway. It cleans out a lot of crap.