Hey Carrie
I’m in book publishing, and I admit I stink at GREP. However, I have come across these very things. And there are a few options.
Now, if you are using metric kerning, you could try to do a regular search and replace. Search for any letter/apostrope/any letter and replace with optical kerning. Sometimes that is enough to give the desired spacing. If it’s not enough, here’s what I do.
Regular Search and replace:
1) Search for any letter/apostophe/any letter and replace with the color red.
2) Search for red apostrophe and replace with thin space + apostrophe [don’t forget to add that apostrophe]
3) Search for red and replace with black
Basically you will have turned red every instance of a letter preceded by an apostrophe and the letter following it. So you will simply add that space before the red apostrophe. And then since you won’t want the red any longer you change all red back to black.
If you are doing a book in color, then you’d want to subsitute a different color.
Hope that’s a good workaround for you.