Now is a good time to cut back. I would give about 1/4 to 1/3 of a cup per day. You do need to cut back gradually. I would start by measuring the amount she has now and giving a bit less than that a day. Every few days, cut back by about 1tbsp per day until you get to the desired amount. Don't forget to give lots of hay for her to eat.
The general rule for the amount of pellets is 1/4 cup per 5 pounds of body weight pet day. Some rabbits don't need that much and other may need some more. I would get a weight on her now and weight her about once a month. If she gains too much, cut back on the pellets some more. If she starts to loose too much then increase it a bit.
Some rabbits will graze the pellets throughout the day while others will eat them all at once. I feed my rabbits twice a day, about 12 hours apart. If your rabbit will eat through the day, the you can give the whole amount at once. If she eats them all at once, then feed twice a day.