No, once something is gifted as a general matter, and once a property is gifted by deed to another person more specifically, it cannot revert back to the gifter. Furthermore, your sister was not the prevous owner--your parents were--and so has nothing to say about its disposition. If there was an agreement between her and your parents that if she paid for the renovatons, she would be able to sell the home at some point and share in the proceeds, it's possible she may be able to sue your parents for breach of contract, but that has nothing legally to do with you, based upon what you write.