I have a 12-year-old peace lily which I received at my husband‘s funeral. I am desperately trying to save it. It seemed to have taken a turn for the worse about four months ago. I babied it, repotted it with fresh potting soil, sprayed the roots with an insecticide, everything I read to do. When I repotted it, I was shocked to see it literally had no roots so I assumed it was root rot. I trimmed the stubby roots and added a root stimulator to watering I used on it last week. It looks so bad now that I really think it’s on its way out. My thoughts now are that because of the unusually long cold winter we’ve had, the temperature in the house may have made a difference. I have to keep it at 60° at night and during the day it’s usually 65 to 70° and I do have a humidifier on my furnace. My heart will break if I lose this plant. Is there anything else I can do for it?
The bad news is that 12 years is getting old for a peace lily. You can find people on the web who claim to have one that is 20 or even 40 years old, but 5 years is nearer the average life expectancy.
Don't break your heart over it. Accept that it's reached the "do not resuscitate" stage of its life. Trying increasingly aggressive interventions to save it won't keep it going for ever.
If you want a peace lily to keep your memories alive, the best option will be to get another one.