The Collaborative International Dictionary of English v.0.48:
Reaffirm \Re`af*firm"\ (r[=e]`[a^]f*f[~e]rm"), v. t. To affirm again. [1913 Webster] ReaffirmanceWordNet (r) 3.0 (2006):
reaffirm v 1: affirm once again; "He reaffirmed his faith in the church"