Source : Webster's Revised Unabridged Dictionary (1913)

Readmission \Re`ad*mis"sion\, n.
   The act of admitting again, or the state of being readmitted;
   as, the readmission fresh air into an exhausted receiver; the
   readmission of a student into a seminary.

Source : WordNet®

readmission
     n : the act of admitting someone again; "the surgery was
         performed on his readmission to the clinic"