Start by teaching her to back off of the line, by wiggling it . I know that sounds goofy, but she needs to learn to follow a "feel" that is put into the rope/leadline.
Start by having her facing you, you about 3 feet off of her. start to wiggle the rope back and forth the tiniest bit while you kind of lean into her and you can use your other hand to kind of "push" the air indi ating with your body, and voice, to "back!" back!". When she takes one step back, stop all action, let the rope drape down and tell her good girl. Do this more until she backs up when she feels the rope wiggle. Remember to escalate your cues from low to high (if necessary) to get her response; always looking for her to respond to the tiniest of cues, but willing to go big to get a response..
you will back her away from you , you not moving your feet. eventually, she will be 12 feet away (if you line is long enough) and you invite her, with the feel on the rope, to walk back toward you. BUT, stop her, with your body language and a wiggle of the rope, when she is 3 or 4 feet away. DO NOT allow her to walk into your space.
sTart enforcing this space of yours EVERY time you intereact with her. ALWAYS.
this is the start; getting her to back away and come back to you, always maintaining your "bubble".
this isnot the whole answer but all that I can type right now.