Are the roots showing from the top of the plant or are they coming out of the holes on the bottom ? It sounds like it may be time for a transplant. Turn the plant on it's side (lay newspaper down on the floor first) and slipp the plant from its pot to see if you have roots showing all around the dirt ball. If you do then it is time to move the plant into a bigger pot. Loosen the roots before you put it in the next size pot, give it some fresh potting soil and then a good drink of water, let the water drain out the bottom of the pot and then give it some more, in about an 1/2 hour. To test for when you have to water the plant --- stick your finger in the soil down to your first knuckle if your finger comes out dry then give the plant a good drink( again water let drain and sit for awhile and then water again) After you you test a few times you will get the feel of how often you have to water that plant. Peace lilies are great because if they become too dry they will faint and if they do take the plant to the sink and give it a really good drink and it will come back . Good luck with your plant.

swindy