You could reward at random time intervals if the behavior persists during the interval (for persistent behaviors like not hitting), or after a random number of repetitions of the behavior (for discrete behaviors). I'm not actually sure why random reinforcement works better than systematic, but I expect the effect to apply here.

The problem of what to reward is harder, but maybe you could make a list of every absolute demand and stick to that? Parents always drop some of their nice-to-haves because otherwise the kid can't do anything right so you're better off letting them draw on the wallpaper if that means they'll stop sticking forks into plugs. (Also the Chaos Legion demands that you ask "Is that actually bad?" when a kid does something unexpected but not so obviously bad you didn't think of it.)