I would say Conduit 2 could benefit from numbers 5, 2 and 1. It already has solved number 4's problem and number 3 doesnt apply to a game like this.
Multiplayer modes might be too late to add at this stage of the game, but I hope the 14 they have are all diverse and not just slightly different from each other like in the first game.
A scoring system at the end of each level would be nice. It would increase replay value a bit. Trying to score higher score in a certain level might motivate people to try the level again. Online leaderboards would be awesome for something like this.