Can’t find anything already said on the forum about this, so I’m suggesting it :
How about making repeatable levels being able to choose the difficulty we’re playing at ? Of course, only maximum unlocked difficulty would award more gems. Many good things already happened to repeatable levels, and I’m greatful for these. But when I struggle several days to improve from one difficulty to the next one, I’d like to be able to watch it work more than once ! It feels a little odd to win only once and loosing so many times.