41 miles is nothing to worry about. For someone young and healthy, you don't even need any serious training for it provided you pace yourself. Go slower than your 10-mile pace, try to consistently eat, don't wait until you feel hungry and gorge yourself. You won't be expending that many calories so your concern shouldn't be to stay as topped up as possible, but having enough to comfortably avoid bonking.
Of course if you want to ramp up the mileage in the next few weeks, that won't hurt. But it's hardly necessary.