How to Divide a Peace Lily
This plant was getting root bound. It is actually seven individual plants. Needs to be thinned and transplanted to a more suitable container. Gently remove plant from the container avoid damaging the leaves and stems. Fill your new containers halfway with a 50/50 mix of potting soil and peat moss. I usually moisten the soil with a spray bottle of water.
Locate the main plant. It is the stems that are a bit thicker and usually located in the center of the growth. You will see new growth growing around this batch of stem shoots. Gently work each new batch of growth loosening the soil from the individual little bulbs and working the roots for each loose going in a downward motion.
Once you have all your new plants sorted you can start to re pot them. Again I like to keep the roots moistened a little. I'm not sure if it helps, but I've had success with re potting so it can't hurt. Place each one in its own new pot that you have prepared and moisten with water till the soil is damp through. Take care not to scrunch the roots, the purpose of re potting is to give the roots room to grow. Cover with soil so the plant stands firm but not packed in. Give them a drink of water. The Peace lilly likes water but they don't like to sit in water, so empty the dish at the bottom once they had their drink. You will notice that they will spend some time being droopy. It's a big shock for them. Give it a little time and in a couple of days you will start to see them thrive and grow.