Yes, keep treating everytime for quite a while yet. Then as others said, start phasing the treats out, reward randomly, but do this gradually.
If you don't want her on the furniture in the first place, rewarding her to get down won't teach her not to get up (though it is great that she is getting off when you tell her to, keep that part of training up).
To keep her from getting up on the furniture, you will have to supervise her and stop her from getting up. Tell her no, or ah-ah!!! when she redirects her attention to you, treat and praise for NOT getting on the furniture. Catch her doing what you want her to be doing in the first place (even if it is not doing anything at all, like sitting or lying on the floor, as opposed to sitting or lying on the furniture), and reward THAT!
If you don't mind her on the furniture, but just want to make sure she gets off when you tell her too, then, nevermind.
