title_body: Convert epub to epub, to do more heuristic processing
upvoted_answer: Use the command-line tool
  
  [Manual]
  
  If you use the command-line tool,
  you can do just this.
  Though you need to make sure the input filename and the output filename differ.
  
  for example
  
  ebook-convert myorig.epub mybetter.epub --heuristic-processing