reflect on vs upgrade

reflect on

verb
  • To think carefully about (something), and give it due consideration. 

  • To give an impression of (used with an adverb). 

  • To access details of (a data type, etc.) at run-time using reflection. 

upgrade

adv
  • Up a slope or grade. 

verb
  • To improve, usually applied to technology, generally by complete replacement of one or more components 

  • To replace with something better. 

  • To improve the equipment or furnishings of or services rendered to 

  • To replace a program with a later version of itself, a version having a higher version number or marketed under a more recent product name. 

  • To improve in condition or status. 

noun
  • An upward grade or slope. 

  • An improvement 

  • An improved component or replacement item, usually applied to technology 

How often have the words reflect on and upgrade occurred in a corpus of books? (source: Google Ngram Viewer )