Aw, but refilming a movie is cheating.
I recognize that ROTJ is the weakest of the originals, but ESB is my personal favorite, in part because of the reveal. Consider it this way: In order for a sequel to feel like part of a larger story and not be seen simply as a sequel, it will need to contain plot information which is absolutely essential to understanding the nature of the primary conflict, information which was not in any way present in the original movie. In this way, ESB excels. Up until the reveal, it is a sequel in every sense of the word. The reveal changes the nature of the conflict established in ANH, presenting the hero with an insoluble dilemma. Vader ceases to be a simple monster and becomes the personification of the conflict within Luke, and is an assault on his very motivation to be a Jedi. ROTJ satisfactorily concludes this conflict, though it leaves all other conflicts by the wayside or conveniently ends them. This is why I believe that ROTJ is a worthy conclusion to the story of Star Wars: it completes the primary conflict.
If Episode 7 is to succeed as a true continuation of the Star Wars story, it will need to redefine the previous entry in order to allow this entry (ROTJ) to present the insoluble dilemma, which in the case of Star Wars seems to be that ultimate power corrupts absolutely: "Take your father's place by my side" or that evil is more powerful than good: "Your feeble skills are no match for the power of the Dark Side". This can be accomplished by showing how the New Republic has become just as dictatorial as the Empire, or it could go in the other direction and show how even the best the Rebellion had was not enough to save it from the Empire. I have chosen the latter, as it has the upside of being completely unexpected, like the reveal in ESB. It redefines the weakest of the original trilogy as the masterstroke of a cunning Emperor, and in a stroke it balances the terms of the next engagement, eliminating many heroes to allow for new heroes, and essentially establishing a villain who is greater than any yet faced.