I recently refinished my Mother-in-law's solid oak coffee table using a red oak stain (my wife's choice) and four coats of polyurethane. She would like it "browner" (her words, not mine). Is it possible to do this without refinishing again?
Have you checked into a tinted polyurethane? Maybe a 5th coat that is tinted "browner" would be the answer. I would do a test over the existing color on a sample first. Otherwise, it's probably live with it or start over. Ain't life grand?