Well I only had 38 on the second run, so I did a third playthrough and here's an 80 score =P
Those ideas sound good, it'll be interesting to see how the game develops.
Two further things I noticed on this run:
1. You can catch a mouse while in tired/sleep state but doing so does not bring you out of the state prematurely, and I would suggest that either it should, or that you shouldn't be able to catch mice (of either type) at all in this state.
2. There are certain spots near each corner where being hit by the dog will result in you bouncing off the wall and landing on the dog again losing two lives in the process, so a limited invulnerability state after each hit might be a good idea. I got caught out by this three times on this recent run because I kept messing up when I entered sleep mode >.<