Brown leaf tips on a spathiphyllum are usually the result of a water issue. If you let the peace lily dry out the tips of the leaves can turn brown from the tip inward. However if you have brown spots on the leaves this indicates that the plant has received too much fertilizer. Yellow leaves are often the result of too much exposure to direct harsh sunlight. Over-watering can also cause a yellow leaf issue with spathiphyllum.

I only re-pot peace lilies when the roots begin to over take the pot. To help you care for your Spathiphyllum I would suggests reading our plant care for peace lilies. (once you click on the link scroll down the page to see the care instructions) There are some tips on how and when to water as well as potting tips. Good luck and keep me posted.