WillC said:Your Peace Lily is reacting to the root division and repotting that you did. The roots are the equivalent of a plant's circulatory, respiratory and nervous system all rolled into one. When the roots are disturbed then the plant will be traumatized - temporarily, at best and permanently depending on how the root surgery was done. I don't know what advice you received on this site.
Yours looks to be in pretty decent shape so far and will probably recover slowly. Warm temps and a location close to a window will help. You will have to pay very close attention to your watering as the traumatized roots are extra vulnerable to both under and over watering.