How should I "up" my calories?

In a 16 year old male, 5'7, and 120 pounds. I used to weigh 185 before restrictive eating. Usually I would eat 800-1000 calories. I excercise for at least an hour a day. Lately I've been working, which has me rolling pizza dough and washing dishes for about 4 hours. After I would go to the YMCA and do 45 minutes swimming, 30 minutes running, 15 minutes biking, and 10 minutes elliptical. Soon I will just start insanity and only swim. Anyway I'm looking to be healthy again so I can increase back to a normal heart rate. Should I do increments of like 200 calories every week or so or jump up to 2500 right away? I'm just so afraid of being 180 again.

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