The Collaborative International Dictionary of English v.0.48:

Revisal \Re*vis"al\, n. [From Revise.]
   The act of revising, or reviewing and reexamining for
   correction and improvement; revision; as, the revisal of a
   manuscript; the revisal of a proof sheet; the revisal of a
   treaty.
   [1913 Webster]

WordNet (r) 3.0 (2006):

revisal
    n 1: the act of rewriting something [syn: revision, revisal,
         revise, rescript]