Why did Voldemort attempt Avada Kedavra at Harry a second time in Deathly Hallows?

Question

Brief explanation behind this question:

In Deathly Hallows, when Voldemort casts Avada Kedavra against Harry in the Forbidden Forest, the spell connects but (unknown to Voldemort at the time) does not kill Harry.

Two chapters later, Harry reveals himself and faces off against Voldemort in the Great Hall. He and Harry talk and Harry claims true ownership of the Elder Wand.

At this point, the best case scenario for Voldemort is that Harry is lying or mistaken, that he (Voldemort) is the true owner of the Elder Wand, and that Harry's attempted resistance will be of no consequence.

Yet Voldemort was using the same wand earlier and under the same conditions (having disposed of Snape, thinking to become the true master of the wand, before meeting Harry in the forest.) He should therefore expect the same result from the same spell, which clearly involved Harry not dying, even if Voldemort can't guess why. Why does he expect a second Avada Kedavra to work any better than the first?

Answer 1

Voldemort attributed Harry's survival's to accidents, not to a pattern.

"One of us?" jeered Voldemort, and his wholy body was taut and his red eyes stared, a snake that was about to strike. "You think it will be you, do you, the boy who has survived by accident, and because Dumbledore was pulling the strings?"

"Accidents!" screamed Voldemort, but still he did not strike, and the watching crowd was frozen as if Petrified, and of the hundreds in the Hall, nobody seemed to breathe but they two. "Accident and chance and the fact that you crouched and sniveled behind the skirts of greater men and women, and permitted me to kill them for you!"

And if there IS a pattern, he convinces himself that it's favorable to him:

"It matters not!" shrieked Voldemort, who had followed every word with rapt attention, but now let out a cackle of mad laughter. "It matters not whether Snape was mine or Dumbledore's, or what petty obstacles they tried to put in my path! I crushed them as I crushed your mother, Snape's supposed great love! Oh, but it all makes sense, Potter, and in ways that you do not understand!

He knows that he's a much better wizard, and can not even remotely conceive of a fact that he is unable to kill Harry - which is contrary to his whole worldview of:

He, the greatest wizard of them all; he, the most powerful; he, the killer of Dumbledore and of how many other worthless, nameless men (Chapter 27)

Answer 2

Voldemort wasn't thinking logically at the time, after Harry's inexplicable survival and unsettling speech. He was so used to Avada Kedavra successfully and immediately solving his problems (since his problems usually took the form of people he wanted dead), that it probably became something of a security blanket to him. By that point he not only knew the spell wouldn't work, but he may have even known, deep down, that he could never kill Harry (although he would never admit it). I believe his choice to use the Killing Curse a second time was more of a final, feeble, stubborn attempt at victory by a man who knew he had lost.

Answer 3

In the forbidden forest, Voldemort used the curse because he thought that since Harry’s mother was dead and her love couldn’t protect him anymore, that he could finally kill him. And then when he found out that Harry was still alive, they had their final duel out in the courtyard after many little talks and small duels within the castle they had their final duel in the courtyard and Voldemort knew he would lose but he wasn’t going down without another fight and he’s just a stubborn wizard who thought that if he did it enough it would finally kill Harry. Technically he could have killed Harry during the final duel because when he used the curse in the forbidden forest, it killed the part of Voldemort’s soul inside of him, so if Voldemort would have struck him with that curse in the final duel, Harry would have died.