This is one problem with appy's, in my opinion, some good ones, just as all breeds have some bad ones. But seems to me Appy's seem to be a bit more stuborn (evil). Not trying to start an argument but I have to disagree with the post that said to use the halter with knots in it (natural horseman halter) and the double up the halter with a neck rope type halter. You want something to give, not the neck muscles or risk a pole injury (horses pole).
I would get a car inner tube or a couple of bike inner tubes, deflated, tie them high on the stout tree and tie the lead rope to the inner tube, this to take some of the tension of the pulling. Use a slip knot for quick release if needed. Then get a lunge whip or long willow branch and give yourself lots of escape room. Tie her stand in back and to the side of her, so not to get kicked, and smack her lightly than harder when she pulls back, remember not to let yourself get mad, you need to quit smacking her the second she steps forward. Stay away from the kicking parts. You want a slip knot in case she goes stupid and goes down, but the inner tubes will stretch quit a bit. Your giving her negitive reinforcment for negitive actions, remember to give her positive reinforcment for postive actions.
JMO
Alan