While I don't think you should ever intentionally wake your baby up for anything, I do agree with Bria.k about pumping. Pump between feedings. Supplies do fluctuate, so don't worry too much. There is also Fenugreek which is said to increase milk production.
Wake up baby for feedings every 3 hours. Don't go too long without feeding, even if it's just for five minutes. Also try pumping. It'll help up your supply.