Parashat Ki Tavo describes kelalot - the curses – from a public perspective; the unique innovation of Parashat Nitzavim is that the curse can also relate to the individual, the family, and the tribe. The Torah therefore emphasizes that he covenant relates to and includes each and every individual, in any status and from any time. This emphasis negates the ability to escape both the covenant and the curse.

Additional References
דברים, ל;