This is also known as a Factory Reinstall, a complete game reset to the software revision specified by the ISO download.
Consider performing a USB backup of Settings & Hi-Scores before starting, since they will be reset back to their factory defaults.
Full game installation at times will be the only mechanism for updating, as underlying operating system changes may be included with the update.
** NOTE: An 8GB or larger USB stick is required for a full installation, larger than 32GB is not recommended & has been known to cause issues.
JJP USB UPDATE PC Instructions PDF Download