Seeing changes to your MIDI remote script can be done in a number of ways.
- All versions: Close and re-open Ableton Live
- Ableton Live 9 & 10: Reloading the current Ableton session also reloads the MIDI remote scripts
- Ableton Live 11 and 12: Use a Beta version of Live and add the Tools > Reload MIDI Remote scripts menu option. Full details of how to do this can be found in the article Instantly Reload MIDI Remote Scripts in Ableton Live.