It's possible it was to wet while in the large pot, but I would think you would still see some smaller roots, but I'm sure no expert on these plants. This forum is for true lilies (lilium. It's also not well frequented at this time of year. You would get more and better responses if you posted this in the houseplant forum. Good luck.

I have a peace lily I brought home from my Grandmother's funeral 17 years ago. It has seldom done what I would call really well but some years it has flourished more than others. Well, a couple of years ago my husband re-potted it (the 2nd re-pot) and he put it in twice as large of a pot than it was previously in and covered the base of the plant (above the roots) by over an inch (maybe more). He also used a fertilizer (don't know what). Since then it has not done well. In fact it has withered to almost nothing. It still keeps trying...growing new little leaves all the time but they wilt, turn dark and die fairly quickly. Now my plant (which once was about 20" high and 15" wide) is about 3 inches tall and 5 inches wide. It is so sick. :(
I am planning to replant it in a smaller pot and see if that will help (and trim any dead roots) but am wondering...how long do peace Lilies live normally? And, is there anything else I should do? What do you think it's problems were?
Thanks,
Cindy