How to upload already compiled code when no changes were made?
You can upload hex file to your board from command line without Arduino IDE.

To get the hex file, use in Arduino IDE in menu the command "Export compiled binary". It will save the hex file next to the ino file.

I assume your board in printer has AVR MCU. Then you can use avrdude from command line to upload the hex file again and again without any compilation.

The avrdude command on Windows is (if started from the sketch's folder):

%LOCALAPPDATA%\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/bin/avrdude -C%LOCALAPPDATA%\Arduino15\packages\arduino\tools\avrdude\6.3.0-arduino17/etc/avrdude.conf -v -patmega328p -carduino -PCOM11 -b115200 -D -Uflash:w:Blink.ino.hex:i


The command line is for the Blink sketch and for AVC boards package 1.6.21