Returning to this, the idea of renewed vows seems pointless either way. For what ends would you want to do this? To alleviate her guilt? Outside of this, what could someone who has already proven they can't stick to vows offer to you by proclaiming them again?
Is she going to start the ceremony by stating that when she said them last time, they were a lie? "This time though, I really mean them," wink.
You've already made those declarations, and she was unable to keep them. Why would saying them again accomplish anything but publicly embarrass you? Perhaps I'm projecting, but I'd certainly find the whole thing embarrassing and a slap in the face, especially if you are disclosing the affair to others.
Personally, I'd be thinking everyone was looking at me like a fool, standing there grinning as she states her declaration of loyalty toward the person she's already cheated on.
This is very much a side point, though; the concerns raised in my previous comment are by far the most prevalent issues to review.
