How to Update Kali Sources List

Edit the /etc/apt/sources.list file

vi /etc/apt/sources.list

Type i to enter INSERT mode

Add the Kali Rolling Repository

deb http://http.kali.org/kali kali-rolling main contrib non-free

Hit ESC to exit INSERT mode

Type :wq to write changes and quit

Then update apt-get to have the new repository take effect.
apt-get update