Hi @justmonica, welcome to Mayo Clinic Connect. I can imagine that you're concerned about your sister's future. While chemo radically improved the leukemia, the hepatoxicity has seriously damaged her liver. I'd like to bring fellow member @gaybinator@jeanne5009 and @rosemarya into this discussion as they may have information about liver repair to share.
The liver has the greatest regenerative capacity of any organ in the body. Have your sister's doctors told her more about the extent of the damage to her liver? What tests have been done? Is it injured beyond its ability to regenerate itself?