Jeston TK1 - What is the fastest way to reinstall the Ubuntu 14.04 rootfs ?

If things go wrong it may be required to re-install the Ubuntu rootfs.
How would you do it ?
Can it be done from the Jetson tk1 board itself ?

https://developer.nvidia.com/sites/default/files/akamai/mobile/files/L4T/l4t_quick_start_guide.txt