Waiting for Inspiration to Strike

I'm revising my second completed novel, PHOTO FINISH, and I'm realizing that I need a whole additional subplot. Something more about the world and less about the particular character conflict. I have a faint niggle of what it ought to involve, but more than that, I'm striking out. I've done this enough, though, that I'm confident that if I continue writing and keep it in mind, inspiration will strike. Here's hoping, anyway.