And it occurred to me that revisiting your characters' pasts could be useful. It will show you just how well you know them for one thing but pasts have a nasty habit of affecting the future and I would be stunned if you found such pasts didn't trigger further stories. A character's past could reveal a lot about their motivations, what they are keeping secret (there usually is something!) and should shed light on why they behave the way they do. The great thing is you can have inconsistency here. Hypocrites are great fun to write for!
So what is the past your characters are proud of? What are they ashamed of? What are they hoping nobody will ever find out (and what would they do to keep things that way?).
I love asking questions to trigger story ideas. They're a great way to get started. Hope you have some fun with the ones above.