This is going to sound like kind of an extreme change, but I think it could add a lot of emotional depth to the film. It is a new scene with Darth Vader, the hard part will be getting someone who sounds like James Earl Jones, fortunately Darth Vader costumes are fairly easy to get a hold of. The scene I am thinking would be Darth Vader having a counseling session through a hologram. So we have him talking to the blue hologram of his counselor about his feelings toward his son who he now knows to be alive, and his feelings of guilt towards having choked Padme, and her having died without him telling her he loved her.

I really think this could add a great deal of depth to Empire Stikes Back, as well as to the whole saga, it also helps connect the good trilogy to the bad trilogy. It would be easy enough to film. Anakin was a pretty emotional character, surely he has to whine to someone, I don't thing Darth Vader could have gone through the gap between trilogies without partaking in a mass quantity of whining. I am sure this might not be a very popular change, but I think it would be worth staking your reputation on Ady. In the end people wont be able to hold themselves back from proclaiming your greatness.