Yes, Phil, I do think cats (and probably dogs too) tend to "tell" us when "it's time."   My tortie Minnie suffered from noticeable arthritis and then urinary incontinence in her 16th & 17th years (I had to put chucks down on the couches and rugs during her last few months) but still acted like she wanted to go about her daily explorations and shows of affection, even as it became harder to get her to drink or to retain any of the liquids she consumed.   Then one evening when I called for her she did not come.   After searching for her for quite some time outside (I always brought her in at dusk or before), I noticed she was standing by my leg, making no sound, not rubbing against me. Her fur was matted and she looked dazed. She let me bathe her--something I normally would have attempted at peril of my own life--and I discovered she had an abcess. It was obvious that she was 'on her way out', so I took her to a naturopathic vet the next day and held her while she slipped away.   The point is, as long as she seemed to be interested in staying alive and doing "cat things," I was not going to "put her down."   I have no doubt she told me when she was ready to go.

I'm glad your kitty seems to be making improvement. My sister's 15 1/2-year-old lab-huskie mix dog seemed to be on death's door about a year ago but bounced back (to being a normal 'old man' dog).   Then last week he seemed to be dying again, but with some TLC and meds he's rebounding somewhat again. In human years he's somewhere between 85 and 100, but estimating this is not an exact science.   I think it's good to realize that sometimes when we think an old pet is "dying" our conclusions may be premature.