I grabbed a lunge stick (?) like the lunge whip but without the whip part and when ever my mare came into me I would give her a tap on the side and ask her to move away and when she did I would stop tapping her, now she hardly does it and she is very stubborn haha. Get after them sometimes I had to give mine harder taps till she decided to finally move. She understood what I wanted her to do but she refused to do it. Don't be afraid to get after them but once they do what you wanted or they're trying to figure it out reward them
if you can't use a whip or a pen, you can toss the end of your lunge line instead. Say "out" and get in an aggressive posture, even if you have to step to your horse and chase them out. keep using it as a cue until it's recognized and responded to just as well as "WOAH" should be
Try desensitizing her to the whip, first over her back, hindquarters, neck, back legs, front legs, next to her (smack the ground), and then send her off. If she's moving forward when you ask with no fit, she's fine. If she throws a fit and won't move forward, she's being disrespectful.
Use the lunge whip pointing toward her hind quarters. Take you hand hold it up toward her face and send her out. When she tries to come in smack the ground with the whip and make her keep going. Do not reward her AT ALL for coming in. Then when you do stop her, make her back up, so she learns there are boundaries