Droopy Peace Lily

Hi

Can someone please advise, I have a little garden at work on my desk and windowsill mainly of spider plants but also including a peace lily.  With the cold weather last week - the heating was turned right up throughout the building and my peace lily wilted so I gave it a nice drink and it recovered very quickly.  However the next day it was droopy again and this time giving it a drink didn't seem to help but it did drink all the water given.  So I thought I would put it in some water and leave it to soak for a while (except a while lasted all weekend because work took over and I forgot to take it out before I went home!)

When I came in this morning the Peace Lily was still very droopy and some leaves had gone a bit yellow.  I have taken it out of the water immediately and I drained off all that I could a couple of smaller leaves in the middle look like they've perked up but the rest is still drooped!

So the question is: is there anything I can do to save this plant or have I murdered it?  Should I be cutting any leaves off or doing anything different.  I have had the radiator turned right down in the area nearest the plants.

I feel terrible!

Thanks

Clare