Most KONICA MINOLTA cartridges have a chip that displays the toner level. When the cartridge is empty, it sends this information to the printer. It is not mandatory to replace this chip when you refill, your printer will work well anyways, but the low toner alert will remain on.
You only need to replace the chip every two refills for a 1710566 cartridge. However, for a 1710567 (high capacity) cartridge, you will have to replace it every time. In any case, you will need a chip for every two bottles.