Harry uses the Ressurection Stone and Dumbledore does not appear. Though Harry meets him a few pages later at "kings cross". So had Dumbledore not "gone on" as he indicated to Harry that he was not dead and that he had a choice. And Jk said that Dumbledore was indeed dead so why not appear in the Ressurection Stone. Had he n Harry not loved each other? I do believe that Dumbledore was important enought to Harry to appear. Remus and Tonks had both just died and they appeared. So why not Dumbledore? I think she was just saving him so that she could write another chapter.