Source : Webster's Revised Unabridged Dictionary (1913)

Regrow \Re*grow"\ (r?*gr?"), v. i. & t.
   To grow again.

         The snail had power to regrow them all [horns, tongue,
         etc.]                                    --A. B.
                                                  Buckley.

Source : WordNet®

regrow
     v : grow anew or continue growth after an injury or
         interruption; "parts of the trunk of this tree can
         regrow"; "some invertebrates can regrow limbs or their
         tail after they lost it due to an injury"