Sure old was pi 4? Older os could not boot all pi, only those beeing out at the time.
One solution is put recent image on new sd card and then put old sd card in sd reader and connect it to usb.
Then login via ssh and run
sudo -i
service RepetierServer stop
mkdir /media/b
mkdir /media/o
mount /dev/sda1 /media/b
mount /dev/sda2 /media/o
now old content is in /media/o/var/lib/Repetier-Server and you can copy it to new sd card /var/lib/Repetier-Server and start the server again. It will now have all your old printers and settings.
# D
# delete installed version
rm -rf /var/lib/Repetier-Server
# copy old data
cp -rp /media/o//var/lib/Repetier-Server /var/lib
# start with new settings
service RepetierServer start
You must activate license - it will see the device is different.
