I strongly recommend putting her on a mostly chicken diet. The best I have used in the past is Wellness, available at Petco. It kept my cat Bunny alive for two years after the vet was sure poor Bunny wasn’t going to make it.
It is expensive but cheaper than an IV.
Use the canned food, Wellness (canned chicken recipe).
http://www.wellnesspetfood.com/product-details.aspx?pet=cat&pid=2
It is expensive but it just may keep her alive. Do not feed rice, potatoes or any grains. Cats are carnivores and do not need them.
Normal pet food formulations have some grains, the rationale being that a cat eating vermin in the wild (rats, mice etc.) would get some from what had been in the digestive system of its prey. And cats can nibble at vegetation. But trial and error may be the necessary thing. When a cat is sick, is not the time to worry about its health for years down the road, if it otherwise won’t eat.