I always look forward to the reprise in a musical, because it's often so much bigger emotionally than the original version. Sometimes the audience is encouraged to sing along. As the author of this article points out, the first time Annie sings "Tomorrow", it's actually a little melancholy. She's trying to encourage herself and the other orphans to look past their dismal situation. At the end of the musical, however, the reprise of "Tomorrow" is a much more optimistic version sung by the entire cast.