There is no reason to drop lower body movements, and depending on wrist injury, you may still be able to train some upper body exercises.
I'm not one to recommend a bunch of machines, since I much prefer free weights, but this is one of those times where they might help you maintain your progress.
You may not be able to make big gains, but it's better than losing what you have. Just look for things that you don't have to grip with your hand. Pec Deck, lateral raises, maybe a rear delt machine, shrugs on a standing calf machine, etc.