There are a lot of different ways I would change Return of the Jedi. I think it’s still an enjoyable film, but it’s definitely the weakest of the OT.
First off, I think the writers completely forgot about Darth Vader’s motivation in Episode V. If you can recall, Darth Vader seemed to be misleading the Emperor into thinking that he would either turn Luke or kill him. But instead, we find in the famous scene where he tells Luke he’s his father, that Vader was actually plotting to get Luke to kill the Emperor for him. Come Episode VI, this plot line is completely abandoned, and I think that’s a real shame. I think it would make the movie 10 times more interesting if Vader was constantly bothering Luke, trying to get him to turn to the dark side so he can kill the Emperor. And at the same time, everyone on the light side can be telling Luke the same thing; kill the Emperor! We can then have Luke plan to turn his father back to the light side, and Vader will ultimately become the one who destroys the Emperor. After all, this was Vader’s problem. He had been living as a pawn of the Emperor for decades. It would be ultimately cowardly of him to get his son to get him out of this mess. And it is his Son that ultimately redeems him. So firstly, the movie should be more about Anakin’s relationship with Palpatine, and how it has soured.
Secondly, I think it would be best to change Endor back into Kashyyyk. In Episode III, the Battle of Kashyyyk is presented to the audience as one of the turning battles of the Clone Wars. We see the Wookies free and fighting in the beginning, then annihilated and forced into slavery at the end. It would be poetic if come Episode VI, the Wookies are the ones to turn the tide of the War again by defeating the Empire.
Thirdly, I think the whole Jabba’s Palace adventure needs to be toned down. Ultimately, Luke’s plan makes NO sense. In the movie, Luke sends R2 and 3PO to Jabba as gifts. Why? Now we have more hostages to save. Then Luke sends Leia disguised as a bounty hunter, and sells Chewbacca to Jabba. Why? Now we have more hostages to save. You see the pattern here? If not, then Leia gets captured rescuing Han, and now we have another person for Luke to save. And thru all of this, Lando happens to have infiltrated the Palace and does… nothing. Wow. What a BS plan.
Fourthly, I think we need to have a more political plot line in the movie. Why is the Emperor building another Death Star? In Episode IV, Tarkin reveals that the Original Death Star was to be used to keep the Regional Governors in line with the Empire. So since the rebels destroyed the first one, are the Regional Governors not following the Emperors will? Just throwing a couple of lines that explains the state of the Galaxy would help tremendously.
Although I think there still needs to be more to change, those are some of the more basic things I can think of.