What does the Torah mean when it writes "Lo es Avoseinu Karas Hashem es ha'Beris ha'Zos ... "?
Rashi: With reference to the covenant that Hashem made with us at Har Sinai, it means 'Not only with our fathers 1 did Hashem enter into this covenant, but also with us'.
See also Or ha'Chayim.
Why does the Torah add the words "Kulanu Chayim"?
Seforno: "You, who made the covenant with Hashem and who are now entering Eretz Yisrael, organize yourselves in a way that the forthcoming generations, who did not enter into the covenant, will fulfill what you are now undertaking.