all better (now)
improved or cured. (Juvenile.) I fell off my tricycle and bumped my knee. Mommy kissed it, and it's all better now.
Completely healed or cured, as in Once we've bandaged it up, you'll be all better. This term is often used to comfort a child who has been hurt. It uses all in the sense of "entirely" and better in the sense of "cured." The usage has been in the language since a.d. 1000.