brush up vs reread

brush up

verb
  • To paint, or make clean or bright with a brush. 

  • To review; to improve an existing but rusty or underdeveloped skill. 

reread

verb
  • To read again. 

noun
  • The act of reading something again. 

How often have the words brush up and reread occurred in a corpus of books? (source: Google Ngram Viewer )