Issue Syncing Apps

I bought and downloaded some apps through my touch, and I want to sync them with itunes so I can download them from itunes as well as well as back them up. But, whenever I click "Sync applications" itunes says "...All existing applications and their data on the iPod will be replaced with applications from this itunes library".

I want the opposite to happen. I want the apps on my ipod to replace what's in itunes. Any ideas?

 

Well, some of them are. But I've since made changes (done on my ipod) and wasn't automatically syncing those apps when I connect to my comp. I'm just worried I'm going to lose the apps that I paid for. Hope that makes sense.

 

Ok, to clarify, I downloaded and paid for the labyrinth on my ipod. Now, I want to sync it with itunes to make sure if I ever restore my ipod i'll still have it saved in itunes. But, when I connect my ipod and go to the apps tab and say sync apps, it says it's going to delete what's on my ipod and sync what's in itunes on my computer.