Along with ensuring that your daycare is properly staffed, not overstaffed and certainly not understaffed, there are other ways of cutting costs without compromising quality.
Food: If you are providing the food for the children in your care, be sure that you are being efficient. Make sure your cook knows how many children will be in care for each meal or snack. Based on average serving sizes, your cook can make sure that they prepare enough food for every child without having many leftovers. If there are leftovers, they must be stored properly and reused in a timely manner to ensure safety.
Utilities: Remind your staff to turn off unnecessary lights. When the class is outside on the playground, there is no need for the lights inside the classroom to be on. If there are offices with a lot of natural light, they may not need electric lights turned on all day every day. Make sure that lights in common areas (bathrooms, staff break rooms, etc.) are also turned off when not needed.
Water: Children are notorious for not turning off water faucets, at least not completely. Help remind them to turn the faucet off completely when they are finished, but follow-up to make sure that they did it. Hopefully it won't take long for that habit to form.
Materials: Hopefully the children in your care have already been taught to use materials appropriately, but if they haven't, this is a teaching opportunity that can save you money. Unused paint can be returned to the paint container rather than rinsed away. If hands can be dried with one paper towel, don't use three. If the child only needs half a sheet of purple paper for an art project, save the other half for another child's project. Toilet paper...ahh, what to say? Half a roll is not necessary for a wipe. Your budget and your plumbing will appreciate this lesson, as well as will those who have to man the mops on overflows.
Not only will these efforts help you cut your costs, but they will also help teach the children in your care how to conserve resources.