I was introduced to death at the very early age of 5 with the death of my grandfather. I barely knew him because of my immature age, yet I was aware of the great commotion surrounding his death. I distinctly remember the night my parents went to his funeral as I peered out the front door as they drove away. It was a cold, northern, winter night.
About 2 or 3 years later, I was again confronted with death by the loss of my beloved cat. I found him as a stray during the winter. That following summer, my neighbor accidentally ran over him with his truck. I was devastated. I knew what death meant. I knew it was absolutely, irretrievably permanent even at that age.
I was also knowledgeable about death even before those instances from having seen depictions of Christ's crucifixion. Try explaining that concept to a child! It's a mind-bogglingly impossible task. Those images disturb me even today when I see them.
At some point in life, each of us comes to accept death and many of us, like myself, come to fear the passings of loved ones much, much more than we fear our own.
My advice is to introduce your daughter to the concept of death now. It's better to learn from you than her own peers. Introduce her to the idea that it happens to everyone and everything because it's part of nature. Let her know there is nothing to fear in death itself because it's a transition from point A to point B that we don't fully understand. Whatever you do, don't tell her about the various, horrible ways we can make that transition. That's the REAL problem and the harshness of life will be her teacher in that regard. All she has to do is watch the 24 hour news cycle...or have an unfortunate pet like I did.
ANSWER:
If the only way your daughter has experienced death is via a fictional character who has been reanimated by Hollywood, then I'll wager she has very little understanding of death. If she believes that dead people can come back to life, now might be a good time to pre-empt the harshness of real life so that it might be easier for her to handle actual death down the road. Talk to her about how Star Wars is fiction and that Leia couldn't be brought back to life.