You keep using that word. I do not think it means what you think it means.
What about the princesses from the Super Mario franchise? It’s a bit of a stretch, but there were some SF elements in there. Some of Bowser’s contraptions could be described as SF, and there was also the 90’s movie with the human/dinosaur parallel worlds created by the ancient meteor and the de-evolution gun.
Princess Zulenna Luzhakna from Girl Genius. (She’s one of the Castle Wulfenbach students/hostages.)
Princess Nell from the interactive book-within-a-book of Neal Stephenson’s The Diamond Age.
There’s a young Princess of Tanith in H. Beam Piper’s Space Viking, but I can’t recall her name.
She has aged incredibly gracefully. I’ll be in my bunk, too. 
If we count fan-fic, Marissa Flores Picard of the Ratliffverse is a royal princess of the planet Essex (because OF COURSE she is…).
Overall, gilt seems to be the norm more than spangly.
Queen Amidala. Although I suppose in order for her to be Queen, it would have been necessary for her to have been born a princess.
No, it appears to be an elective monarchy, she mentions having been elected. Also, she’s Queen of Naboo, not Thneed.
It’s easy to err, the prequel’s confusing,
Confounding, dumbfounding and always bamboozling.
A mistake in the making and serving no need, so
Much like a laser that is fired by Greedo.
“Much like a laser that’s fired first by Greedo” scans much better.
I have to disagree. The “first” ruins the meter. At best, I could see it as:“much like a laser first fired by Greedo” but that undercuts the joke of the “so” on the previous line.
Zeetha (Daughter of Chump) is also a princess - or, properly, “royal princess guardian of the lost city of Skifander”.