Interestingly, killing enemies will no longer provide you with health or missile replenishment. Instead, tilting the Wii Remote vertically and holding "A" can replenish your supply at any time. The same can be done in for health as well; if your health dips into the red, tilting the remote and holding "A" will replenish one energy tank.
I don't particularly like this unless there is a limit or recharge time for it...