Amane could not ready Charlie's expression but she did notice the jealousy and hope in Charlie's voice. It seemed as if Charlie still held some hope for Amane to return to her real self.
But death was an irreversible process. If you aimed to bring a soul back from the cycle of rebirth, then you had to pay a heavy price. And the thing that came back was no longer a soul, but a harbinger of death and destruction.
It was something everyone wanted to accept and move on with their lives. There is no need for anyone to try such a dangerous thing.
"I don't particularly care about my parents. They have been dead for most of my life and I have accepted that outcome. People who had been left in the past should remain there."
Amane very subtly told Charlie Suzuki to give up on Amane as well. It had been centuries and there was no chance of her coming back.