Have you tried whistle training

blow the whistle two short blasts is normally enough whenever you put her food down and have some high value treats to train her with, show her the treats so that she knows what she is going to get when she comes back and practice this first in the house then in the yard, then in parks etc, always give her lots of praise when she comes back and a high value treat, you could try spliting her meals up into smaller portions and using this as the reward for coming back, if she does not return she does not get that portion of food.

Do you use clicker training? I find this helps a lot with recall and off lead/leash training

Have you tried recall training in an unfamilar place where she is less confident, have you tried hiding from her etc