1
general::
Recovering one's health, as in I heard you had the flu, but I'm glad to see you're on the mend. This idiom uses mend in the sense of "repair." [c. 1800]
American Heritage Idioms
2
general::
Phrase(s): on the mend
getting better; becoming healthy again. • I cared for my father while he was on the mend. • I took a leave of absence from work while I was on the mend.
McGrawhill's American Idioms And Phrasal Verbs