1)
Why will they recognize "Ki Ani Hashem"?
1.
Malbim: They will recognize My Elokus more when I bring the destroyer to their land.
2)
It already said above (3) that Pharaoh said "Li Ye'ori va'Ani Asisini." Why is this repeated?
1.
Malbim: Now it discusses the third Churban of Egypt, in Nebuchadnetzar's 27th year ? this was for attributing all power to the river and to himself; Pharaoh claimed to be divine. This was eight years after the Churban for not helping Yisrael. Also after that Churban, in which part of Egypt was destroyed, Egypt's kingship was not totally wiped out.
