Talk to your vet and see if cyproheptadine (Periactin) might work for Coco. Periactin is a human antihistamine, but works as an appetite stimulant for cats. It comes as a 4 mg pill, but most people on the CRF-Support-Site recommend starting low, 1/4 pill every 12 to 24 hours, and increasing until effect. My parents cat, Samson, only needed about 1/6 of a pill, twice a day. Too high a dose can cause either sleepiness/lethargy, or conversely, can cause agitation and vocalization. Both side effects will go away when the drug is metabolized out of the system. I have used it with Cleo and it also worked for her. Some people have said that it doesn't work for their cat, so I guess it might not work for all. Other people have had good luck with using Winstrol (a steroid) for appetite stimulation, but I'm not real fond of using steriods, unless the benefits outweigh the risks. Winstrol is also used for red blood cell production when cats become anemic from CRF. I have used Epogen for RBC production with great results. I would consider Winstrol for this indication, if Epogen didn't work.
Other methods for encouraging eating include: Warming the food to make it smell better, sprinkling Brewers Yeast on the food (some cats go crazy for it, Cleo was never affected by it.) Another trick is using Bonito flakes sprinkled on the food. Bonito is dried fish flakes (you can get this in oriental food stores.) Some pet food stores sell it as Kitty Kaviar.