I agree with Ozzysmom (and Lily, too) that she has gotten the idea that "no" means a game to her.
She needs to submit to you as alpha. With a puppy, I put them on their back in the crook of my arm-their head at my elbow-like holding a baby-I can hold the back feet with the hand on that arm and then hold the chest with the opposite hand. They need to quit squirming and to make eye contact with you before you release them. This shows them that you are the boss. Sometimes or maybe the first few times you do this, they will not like it at all...they will squirm, whine, nip, anything to keep from giving in to you. But eventually they will...don't be mean or loose control, just be firm.
The mommy chi of the two pups I have right now, disciplines by rolling them on their back and really biting on the neck-growling at the same time(it really looks mean)-they will quit what they are doing and lay really quiet until she leaves-and then they are off to another adventure, but they do not continue the former one.