We have a mare that can get in moods and trys to run away. But other times she walks right up to you. When she runs, I let her run and don't chase her. Then once she stops, start walking towrds her once she looks at you. Then when she looks down, stop. I do this everytime she runs away, and she lets me walk right up to her! :) Good Luck!!
Also, spend time out there with her and don't even pay attention to her. Sometimes they will walk right up to you and they learn that just because you are out there doesn't mean they will be worked. Build a strong, trusting relationship because that is what connects you and the horse, not just riding/working. :)