The Collaborative International Dictionary of English v.0.48:

Retrace \Re*trace"\, v. t. [Pref. re- + trace: cf. F. retracer.
   Cf. Retract.]
   1. To trace back, as a line.
      [1913 Webster]

            Then if the line of Turnus you retrace,
            He springs from Inachus of Argive race. --Driden.
      [1913 Webster]

   2. To go back, in or over (a previous course); to go over
      again in a reverse direction; as, to retrace one's steps;
      to retrace one's proceedings.
      [1913 Webster]

   3. To trace over again, or renew the outline of, as a
      drawing; to draw again.
      [1913 Webster]

WordNet (r) 3.0 (2006):

retrace
    v 1: to go back over again; "we retraced the route we took last
         summer"; "trace your path" [syn: trace, retrace]
    2: reassemble mentally; "reconstruct the events of 20 years ago"
       [syn: reconstruct, construct, retrace]