when you repotted it, was the soil soggy? did you see roots?

it could be rot, which you can try cutting off the bad roots, and dusting tie remaining ones with a rooting hormone (or giving it willow twig tea, which contains the same chemicals) it could be transplant shock, from which it whould recover.

Hi Heather,

Here's a link to some basic information about your peace lilly that may help you, or if this doesn't help, try posting on the House Plants Forum--you'll get a wider variety of people who know specifically about house plants.

Good luck,
Skybird

Here is a link that might be useful: Spathiphyllum - Peace Lilly