1)
Why did he mention that fire already descended twice?
1.
Malbim: If the fire was to instill your fear on people, we already saw your power twice! If it was because the first spoke brazenly, I supplicate!
2)
He already said "Tikar Nafshi b'Einecha" in verse 13. Why did he repeat it?
1.
Malbim: The first time, he asked that Eliyahu not kill him and his men. This time, he asked that Eliyahu agree to come to the king, lest the king kill the Sar for not taking Eliyahu by force 1 .
1
Did the king not realize that if they try to take him by force, Eliyahu will summons fire to kill them?! (PF)