The Collaborative International Dictionary of English v.0.48:

Reattach \Re`at*tach"\ (r[=e]`[a^]t*t[a^]ch"), v. t.
   To attach again.

   Note: The object reattached may have been an integral part
         which had never been "attached" (trans), e.g., to
         reattach a severed finger.
         [1913 Webster +PJC]