Finally got the printer up and running again. Since the move of the server, my printer was not connected to the net. But thanks to Ebay I got myself an old HP Jetdirect EX. This device has a parallel port for the printer and an ethernet interface. It gets itself an IP-number from the DHCP-server and accepts raw data on port 9100. I only had to tell lprng to use this netdevice instead of the local parallel port.