The Collaborative International Dictionary of English v.0.48:

Reassume \Re`as*sume"\ (r[=e]`[a^]s*s[=u]m"), v. t.
   To assume again or anew; to resume. -- Re`as*sump"tion
   (r[=e]`[a^]s*s[u^]mp"sh[u^]n), n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

re-assume
    v 1: take on again, as after a time lapse; "He re-assumed his
         old behavior"