What is the G-code to set the retract length?

good_idea

Hallo! 
I am trying to calibrate the retraction length using PrusaSlicer. For that I need to change the retraction length at sertain heights (let's say every 2 mm) while printing two objects at a distance from each other. That is easy to do in PrusaSlicer by inserting the G-code commands M207 S.. F.. for other firmwares (like Marlin, RepRap..). Which G-code should be used with Repetier firmware? 
Thank you in advance!

Repetier

Actually you should not really change retraction length in repetier-firmware during print. The only way to change it is with M205/M206 changing the eeprom settings. 

Better is to define the retraction length in slicer and not rely on G10/G11 in this case.

Why is it required to change the retraction length during print? This is just to reduce pressure for oozing and it either is enough or not, but never heard that you need to adjust it.

good_idea

Sorry, I wasn't clear. I don't want to change anything during print. I need to prepare a calibration G-code. Let's say we need to calibrate the retract length for a new plastic. We take a model (two separate towers) and slice it with PrusaSlicer. PrusaSlicer supports a feature "insert custom G-code at layer" - to insert G-code commands at any height.  I want to insert a G-code defining the retraction length at each mm height change. Example: 
Print with retract=0 from z=0 till z=1mm;
Print with retract=0.2 from z=1.2 till z=2.0;
print with retract=0.4 from z=2.2 till z=3.0;
etc.
And when slicing is complete we send it to print and we don't change anything during print. 
For example here https://help.prusa3d.com/article/insert-pause-or-custom-g-code-at-layer_120490 
they insert M104 command and print temperature tower. 
If I am again not clear the above mentioned link has a short and clear explanation. 
Thank you! 
And a separate thank you for nice firmware! And luck and patience with version 2.0!

Repetier

Ok for calibration it makes sense.

Find the correct M206 code by logging commands send in one window and then in an other open eeprom editor and change the setting. On save you will see a M206 with some parameters and X with value you want. That's the command you want.