WordNet (r) 3.0 (2006):

smarten up
    v 1: make neat, smart, or trim; "Spruce up your house for
         Spring"; "titivate the child" [syn: spruce up, spruce,
         titivate, tittivate, smarten up, slick up, spiff
         up]
    2: dress and groom with particular care, as for a special
       occasion; "He spruced up for the party" [syn: spruce up,
       spruce, slick up, smarten up]

Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "smarten up":
   adorn, array, beautify, bedeck, bedizen, blazon, color, dandify,
   deck, deck out, decorate, dizen, doll up, dress, dress up,
   embellish, emblazon, embroider, enrich, fig out, fix up, furbish,
   garnish, grace, gussy up, ornament, paint, prank, prank up, preen,
   prettify, primp, primp up, prink, prink up, redecorate, redo,
   refurbish, set off, set out, slick, smarten, spiff, spruce up,
   titivate, trick out, trick up, trim