renew vs retrofit

renew

verb
  • To make (something) new again; to restore to freshness or original condition. 

  • To replace (something which has broken etc.); to replenish (something which has been exhausted), to keep up a required supply of. 

  • To repeat. 

  • To begin again; to recommence. 

  • To make new spiritually; to regenerate. 

  • To extend a period of loan, especially a library book that is due to be returned. 

noun
  • Synonym of renewal 

retrofit

verb
  • To give new characteristics or make alterations (to someone or something) to suit them to changed circumstances. 

  • To supply (a device, structure, etc.) with new components or parts that were not previously available or installed; to modernize. 

  • Synonym of backport (“to retroactively supply a fix or feature to a previous version of a software product at the same time or after supplying it to the current version.”) 

  • To supply a device, structure, etc., with new components or parts that were not previously available or installed. 

  • To add or substitute (new components or parts) that were not previously available for or installed in a device, structure, etc. 

noun
  • An act of supplying a device, structure, etc., with new components or parts that were not previously available or installed; a retrofitting. 

  • A change made to a device, structure, etc., by introducing components or parts that were not previously available or installed. 

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