So sorry to hear about your kitty. I went through a similiar situation. My 14 year old cat started going through liver failure. After many, many tests, we were never able to determine the exact cause. I had to inject fluids into her several times a week. Eventually, we decided not to do that any longer, as it was causing her great stress.
We decided that however long she had left, was going to be the best it could be. She started begging like a dog (anything we were eating, she wanted), so she got whatever she wanted. Extra sharp cheddar cheese was her fav!! Well, she lived another 3 years (we never thought in a million years that would happen).
My advice is, if your kitty doesn't have long left - make it the most enjoyable for kitty as possible.