I think it would be good to track how close you are to the next badge on your app - i.e. if you are 2 floors away from reaching the next badge, send a push notification through and it'll help people want to earn more badges. If you are 2,000 steps away from the next badge, send a notification through the app or screen on your Blaze (example as I have a blaze). I would like to know how many more life-time miles I need to get to the next badge so they're not a random surprise, and it keeps me wanting to hit a target.
If this could be built into the tracker and released through an update, I think it would help keep people motivated to earning the next badge you offer.