Work out and stretch your legs a lot before and during ski season. Don't forget the abductor/adductor work outs. They make you look stupid and girly, but they are essential to keeping those muscles strong.
Also, if you have problems pre-releasing, don't keep cranking your din to infinity. Check to make sure your forward pressure setting stays in spec first. Then if it keeps happening, trash that binding. It clearly isn't made for the pressures of freestyle skiing. Go get something with more elasticity that will hold you in on strained switch landings and clashes with rails, while still remaining at a low din setting.