Unfortunately reward and punishment are perceptions on the receiving end. I was thinking more along the lines of the more painful outcomes with kids having anxiety, oppositional behavior, underachievment, where homework could compound issues by creating a nasty bit of cognitive dissonance.
It would be an epic effort to find a worse consequence for them not do homework than the one homework has already. I'm all for avoiding the under-skill level drills, but push comes to shove finding things like timing to bring fun or some alternate mindset to play seems the most hopeful.
Repetition is not the same as deeper analysis; indeed that's another survival mechanism. Finding strange connections between the numbers on a math page, counting words used, etc. What would be really nice is a context where that type of analytical thinking is led and students are encouraged to apply and share those as they explore the more foundational skill stuff (actually I think I read that Exeter Academy does that and has impressive results in competitions.) EPGY sounds smart too.
