What is the theme in Replay by Ken Grimwood?

Loss and Meaning are important themes in the book. As Jeff moves through the reiterations of his life, he becomes keenly aware that nothing is permanent. Jeff gains money in his second replay, but he loses his wife Linda. Jeff gains a daughter but loses her with a horrible finality when he dies again in October, 1988. In his next replay, Jeff gains a new family, his college girlfriend Judy and two adopted children. However, he cannot keep them. When he dies again as 1988 rolls to a close, Jeff realizes that anything he gains in life—family, friends, money—is not permanent. Eventually, he will lose everything and cannot even take comfort in the idea that what he's worked for goes on without him after he's gone.