Cutting is done with diet and cardio/high intensity training. If you want to keep what muscle you have, you need to keep the heavy lifting. Higher reps to 'cut up' is a bullshit myth perpetrated by people who didn't know what the hell they were talking about.
Lift heavy. If you're trying to lose fat, keep your caloric intake lower than your maintenance calorie requirement. You can do that by cutting some calories, or by increasing your output (cardio and/or high intensity). DO NOT try to burn more calories by lifting lighter weights for higher reps. That's a sure way to lose muscle.