From the original Krackattacks article:
Should I change my Wi-Fi password?
Changing the password of your Wi-Fi network does not prevent (or mitigate) the attack.
The original paper states the hack requires the passwords to be cracked by brute force. . . and the authors assume that will be easily done. It doesn't necessarily mean it will be done in a short time. The more complex the password, the longer brute force cracking will take.
As I understand it, the cloning of the Router does not copy the settings or any data on the original WIFI Router such as the contents of the password files. The cloning merely replicates the MAC addressing. . . and inserts itself in place of the original Router. it's the WIFI packet encryption keys that are being forced to be reused multiple times by the hack when normally they are supposed to be replaced with each packet, not the WIFI passwords themselves.