What does Bud mean when he says "Here we go again" at the beginning and end of Bud, Not Buddy by Christopher Paul Curtis?

At the beginning of the novel, Bud says, "Here we go again" just as he is being told that he has been accepted into a new foster home (Curtis 1). Bud's exasperated comment reflects his negative reaction to being sent to another foster home. Bud mentions that he has already lived in two previous foster homes and is not excited about being sent to a third.
At the end of the novel, Bud is looking at a picture of his mother and thinking about his journey. Despite all of his struggles, Bud has finally found happiness living with The Dusky Devastators of the Depression and looks forward to his future. Bud then says, "Here we go again, Momma, only this time I can't wait!" (Curtis 236). The second time Bud makes the comment he says it in a positive way. Bud is optimistic about his future and has hope that he will enjoy his new life with the band. Instead of being upset about going to a new home as he was at the beginning of the novel, But is excited and looks forward to the future at the end of the story.