Udev uses the inotify mechanism to watch for changes in the rules directory, in both the library and in the local configuration trees (typically located at
/etc/udev/rules.d). So most of the time you don't need to do anything when you change a rules file.
The udev rules are only applied when a device is added. If you want to reapply the rules to a device that is already connected, you need to do this explicitly, by calling
udevadm trigger with the right options to match the device(s) whose configuration has changed, e.g.
So here is the reloading rules and triggering them.
udevadm control --reload-rules && udevadm trigger