Also, the GitHub page doesn't actually mention uninstalling
KFMon before an install (and doesn't actually mention *anything* about treating a reinstall any other way than a first-time install), it mentions uninstalling
fmon, which is not the same thing, and is something that no longer actually exist anyway

.
TL;DR: Just install it again, whichever way you prefer. Manually, OCP, anything'll do.
There's only so many ways I can say: just unzip the install zip at the root of the device over USB and let it do its thing.