Not sure if this has been suggested before.
Instead of having a limited number of lives per checkpoint, I think it would be good to have a limited number for all checkpoints. Here's how it'd work...
There would be a global setting somewhere, where you can choose the starting number of lives for a level. At default it would be at infinite, which would work exactly as it does now. But you can also tweak the number, in which case you'd get a new icon on the HUD whilst in play mode showing the number of lives you have left. So say you start with 3 lives. Whenever you die, no matter where you are, you lose a life. Get to 0 and you have to start again.
Then, there'd be a new type of bubble - the Life Bubble. Same size as a Prize Bubble but has a sackboy icon in or something. Whenever you collect one, you get an extra life.
There's quite a few possibilites you could do with this. For one thing, you could make hidden areas which are worthwhile visiting iof prizes and high scores aren't your thing. You could have a stack of lives which will come in useful later in the level. You could also get an extra bonus 1000 points per life you have left when you reach the scoreboard, so the more you collect and the less you lose, the higher your score will be.
Also, another suggestong that goes with this idea is an extra setting on the scoreboard that allows you to choose if you spawn there once you run out of lives. Then you could make multiple life survival challenges.

