The Collaborative International Dictionary of English v.0.48:

Encore \En`core"\, v. t. [imp. & p. p. Encored; p. pr. & vb.
   n. Encoring.]
   To call for a repetition or reappearance of; as, to encore a
   song or a singer.
   [1913 Webster]

         [Rebecca] insisted upon encoring one of the duets.
                                                  --Thackeray.
   [1913 Webster]