I forgot to mention the FSN newsletter about Caring for Peace Lily. It has a lot of good information about the plant and how to take care of it.

You can split your peace lily into two plants (one for you and one for your mother). To reproduce a peace lily in this way, you begin by removing the plant from the pot. You will need a sharp knife. Take the knife and cut the peace lily from the bottom up. Cut through the roots but make sure there are ample roots to support the foliage.
Once you have divide the plant, re-pot each one in a separate container. Choose a container that has drain holes and use a soil media designed for house plants (your local garden center should have this soil). Make sure the plant is potted at the same level as the original plant (soil level should hit at the point in which the roots attach to the foliage). Water the plant and keep moist but not soggy.
The plant may go through transplant shock. You can use a little Vitamin B to help with the shock (your local garden center should have this as well). Do not become alarmed if the plant wilts a little. Do not give it extra water — wilting does not mean the plant is dry. In a couple of weeks you start to see some new growth. You can resume fertilization only after you start to see new growth.