She may have gotten used to the LOW voltage fencer at some point, and now just doesn't care.
Have you checked your fence for being "" H O T "", it should spark at least 1/2 to 3/4 inch or better when you lay a plastic handled hammer against the post itself and then slowly angle it toward the wire. It should really snap.
I have never had any luck with the braided wire though, it has to be smooth and about 12-14 gage to work the best. The horse wire stuff is OK for horses, but cows are another story.
Check your fence at it's farthest from the fencer, and if doesn't spark really hood, meybe you should invest in one that will knock her socks off !! hehehe
It doesn't take long when they get a good hot shock before they quit trying it!
Good luck -- some times you really have to burn em once really good for it to sink in!
Terry