After installing your new cartridge, the printer will indicate that a 'used' cartridge has been installed.
When the message appears, press 'OK' to continue. You should now be able to print as normal.
This error should only appear once for each cartridge.
The page count and toner level information will no longer be shown on the Supplies Status page after completing the above step.
You should be able to judge whether your cartridge needs replacing by monitoring the print quality for any signs of deterioration or fading.