If I change the format and design too much it won't be a Zone Runner game, it'll turn into something different and thats something I have an issue with. Yes, the game is moreorless "more of the same".
Then again, so were the Locked games! And In The Pit!
Familiarity can be a good thing but I do respect your opinions as not everyone will like the games
If you add new features it will still be a Zone Runner game I think, just a much better Zone Runner game. I understand where you're coming from with "more of the same", but ideally a sequel is supposed to be an evolution of the formula. Besides it would still feel familiar, just with extra cool stuff which makes the game better. Don't hold back just because you don't want to break the simplicity.
I guess in the end it will come down to how well the levels are designed.
You could add some extra depth into the game with something like branching paths or bonuses for passing consecutive levels really fast or without dying.
If I was to make a game like this I would probably look to Bubble Bobble for inspiration.