How To Increase Breast Milk Production?

Hi there... I have a 3 year old son who stopped breastfeeding at 5 months when my milk dried up becasue I was unable to pump at work. Since then, I have always had discharge (looks exactly like colostrum from before my milk ever came in) from my breasts. It has decreased slowly ofer time and now it is only one breast and if i squeeze the breast, I can produce a few drops each time, even if I do it over and over again. Is this related to breastmilk or something else entirely? I run a daycare through my home now and have the ability to pump if I was producing again. I do not want to breastfeed my toddler, but have thought about freezing the milk and allowing him to drink it without knowing where it comes from due to the nutritional benefits. Is this possible for me to do if I start pumping again? Can I get my supply back (especially since I am only discharging from one breast)