Is she wearing a haulter already? When you get her do you have to put the haulter on as well as clipping her to the lead rope? If not, then you should always put her haulter on when turning her out so she's easier to get.
You could also walk up to her with the lead rope behind your back, sometimes horses are scared of lead ropes for some reason.
Also, try different treats besides apples, maybe she doesn't like apples. I used carrots when this happened to me.
Maybe whenever she lets you get her you should give her a treat, and then she will WANT to come when you call her. Find what treats she likes best! On the other hand, then she might get nippy if you decide to do this...