I don't know the movie name, but I think I know the plot.
In an alternate timeline Princess Leia falls down a time vortex and winds up on earth in the 20th century. While there, she decides to become a drill sergeant at a school for ninja's. Her intent? To wipe out the empire - More specifically, the British empire. This she found easiest to do from Asia, which is where she decided to set up base. After infiltrating multiple colonies with her army of rebel ninjas, she successfully started many revolts and revolutions destroying the Brits from the inside. She lived to a ripe old age, and died happy knowing she was the leader of the group the took down the evil empire.
Her army of Ninjas continue her mission though, and infiltrate and overthrow every empire they came across. Over time though, the mission is jumbled and the focus drifts from the diffusing of empires to the revolutions and revolts of governments. The group looks to the first successful take down and use it as a blueprint, and strives to take down more and more states like the British. They fix elections and start wars, all behind the scenes. Despite all this, their enemy lives on. They only have one course of action - to go to the past and stop it from ever happening.
The army of ninja, I suppose you could call them space ninjas now, find themselves a long time ago in a galaxy far, far away. They infiltrate the nearby planets until many of them are in high positions, while also teaching their technology of cloning and other advanced sciences to the right people. Before long, the evil republic starts to crumble and they are able to swoop in and dismantle the democratic state as they have done so successfully so many times before. They smile on a job well done, a smile knowing their leader Drill Sergeant Leia would be proud to know they completed her mission.
So if I had to venture a guess for the movie name, I would go with Star Wars Episode 0: How Princess Leia created the Empire.