We had a filly running on,,,,oo........maybe 15 acres? Barbed wire. Guess what? She kept jumping it. ANd do you know what happened? She got caught one time. She absolutely TORE up her back legs. She had cuts all over one, and tore the tendon right through in the other leg. Had to be in a full leg cast. She would MAYBE only be breeding sound, but there was a chance she wouldnt. Anyway, it would have been hundreds of thousands to fix her leg, with just a chance of full recovery. So we had to put her down.
So my advice- fix the fence, divide it up in good fencing so she wont get hurt.