1)
Having said "Al Tashcheis Amcha ve'Nachalascha" - in Pasuk 26 - why does Moshe repeat "ve'Heim Amcha ve'Nachalasecha" here?
1.
Ha'amek Davar: In Pasuk 26, he was giving a reason as to why Hashem should have pity on them and not annihilate them; whereas here he is giving a reason as to why He should not tolerate the accusation that Hashem hates them - save them just as a person would not allow others to slander one's errant son, even when he himself is punishing him.
2)
Why did Moshe need to say "ve'Heim Amcha ve'Nachalasecha"?
1.
Da'as Zekenim, Rosh and Hadar Zekenim (in Pasuk 24): To counter Hashem's statement "Lech Reid ki Shicheis Amcha" (referring to Yisrael as Moshe's nation). 1
