The kind of diet your girl may need would be determined by the type of damage to the liver and how bad it is ;) Your vet could probably advise you about this ;) Or once you know exactly what the damage is, you will be able to find out more and give her an appropriate diet.
This website will explain how the liver works and how it is affected by different types of liver disease. Also how different diets can help with the different diseases. I realise that your little girl isn't human, but the information will still be useful in helping you understand and hopefully help you find something to help. I also realise that she doesn't have 'liver disease' as such, but liver disease damages the liver, so there are some similarities
http://www.britishlivertrust.org.uk/liver-information/diet-and-liver-disease/Hope this helps some. And hope your little girl continues to improve.