this is what Bostonrott told me Im quoting her
If she knows how to heel, and she gives you "lip" again, I'd put her into "boot camp heeling." I.e. dog screws up, you give a firm verbal correction, and then immediately start making the dog work briskly and with purpose. This will get the message across to the dog "I am the leader, you listen to me."
That is what I do with Gypsy and it works wonders she used to growl meanly when I would try and do things to her, lately she is just grumbling softly (in a nice manner) and not growling like she wants to eat me!