Write in a good female villain or an experienced female hunter or a helper in the human world. There are enough possibilities that don`t end up in a Lana Lang.

I may be a lone voice on this, but I could stand to see Missouri again to play a part like this. I don't think we particularly need a female villain, since we had Meg last season, but yes, a female hunter, or someone like that, would be nice. So long as the focus stays on the Winchester family dynamic, which I think is what most of us are watching for.