I would keep the 30-06. Below are chart clips from a download program provided by Federal. It allows you to easily compare their different cartridges for different calibers. I think it is great for making comparisons like the one you are contemplating now.
Sure the 7mm shoots a little flatter and has a little less wind drift and more energy, but none of that would be enough to really matter when hunting inside 400 yards. (Just look at the numbers below.)With same weight bullets of comparable BC the 7mm has about 150 feet per second on the 30-06, but that comes at a cost. Added recoil and more expensive ammo. Plus the 30-06 would be a little easier to load as it is not a belted case.
The 30-06 is a very fine cartridge for hunting. Usually a step up in cartridges like this gains you about another 100 yards of useable shooting distance.