I never re-freeze thawed meat, and do what the others have suggested as far as separating the meat into pound portions (or whatever size you use, I imagine I'll have to make the portions bigger soon).
You can, though, cook thawed mince and freeze it for up to two or three months. So if it's loose meat you want, for spaghetti or whatever, and you've thawed too much, you can cook and freeze it.