The real way for him to escape the loop, of course, is to finish his novel.
But we all know that’ll never happen.
The annoying thing about groundhog daying is that you can’t bring stuff with you between loops. All the progress he makes on his novel is lost the next day. And what if he does write the whole novel in a day and it’s all wiped when the day resets? That would be a kick in the ass wouldn’t it?