Autoleveling in repetier firmware is done using G32
- G32 S<0..2> - Autolevel print bed. S = 1 measure zLength, S = 2
Measure and store new zLength
But you need to configure the firmware to have support for it compiled in as well as controlling the servo fo the bltouch to deploy the probe and retract it. In this forum you will find several threads describing this. The host software has nothing to do regardless which, autoleveling is done completely in firmware. Only when compiled you can change some parameter for leveling/probing in the eeprom settings.