Safely losing 25 pounds by December is impossible. I'm not sure how you've lost the 35, so far, but if you're stuck, try changing your routine. Increase/decrease your exercise and calorie intake. If you continually do the exact same thing, your body gets used to it and simply expects that.
Changing your routine every few days will keep things more "upset", so your body won't have a chance to get used to it.