Infix Pro PDF Editor can replace a page with a page from another document. 

  1. Open a document whose page you want to replace
  2. Choose Pages->Replace...
  3. Choose the document supplying the new page.
    Replace Page options
  4. Choose the page from the donor document. 
    The donor document is unaffected by this operation - a copy of the page is made before insertion into the current document.
  5. Choose the page to be replaced in the current document. 
    The chosen page will be permanently deleted. 
    Make sure you have a backup of the document in case something goes wrong.