Applies to: Launchpad Mk 1, Launchpad Mk 2, Launchpad mini, Launchpad S
If you do not want your Launchpad buttons triggering your software instruments (e.g. Drum Rack) at maximum velocity (127), Ableton includes a handy plugin called 'Velocity' which is ideal for limiting the velocity to your ideal specification.
Select the MIDI track you want to limit in Live, then go to MIDI Effects > Velocity in the 'Live Devices' section on the left of the screen.
In the plugin section, adjust the 'Out Hi' setting to whatever you would like your maximum input velocity for that track to be.
You can raise the 'Random' parameter in the velocity plugin to give your playing more of an human feel.