OK, glad to help. Peace lilies are low light, but not in the dark. That's why they make good office plants.
When you water, flooding is best, so the salts can drain out. See the orange-ish and white stuff on top of the soil? That's salt build up. You can scrape it off and give the plant a shot in the arm with an inch of new potting soil.
Keep moist but not soggy, and it won't die if you forget to water once in awhile.