For this issue, you may want to try a utility, called gdisk, I suggest trying with the "v" verify command, and then with the "r" recover command. Please take a look at the man page before hand to get a gist of what else it can do http://www.rodsbooks.com/gdisk/gdisk.html
Also as an alternative, I havent't tried, but heard that this route may actually be more user friendly is a program called FixParts (and maybe the better option for what you want to do. Here is the website for it: http://www.rodsbooks.com/fixparts/
I hope it helps, please report back your success! ^^
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