come back vs regrade

come back

verb
  • To retort. 

  • To return to one's possession, especially of memories. 

  • To return to a former state, usually a desirable one; to become fashionable once more. 

  • To return to a place. 

regrade

verb
  • To regroup or reassign. 

  • To change the classification of (potentially secret documentation). 

  • To grade again, give a new grade or grading to. 

noun
  • The act or process of grading again. 

How often have the words come back and regrade occurred in a corpus of books? (source: Google Ngram Viewer )