A method of refilling a supply of printing fluid in a printing unit. The method comprises the steps of removably mounting a dispenser unit of printing fluid to the printing unit so as to align and engage a plurality of outlets of the dispenser unit with a plurality of inlets of a plurality of printing fluid storage chambers of the printing unit, the dispenser unit being configured so that only one outlet of the plurality of outlets connects to printing fluid stored within an enclosure of the dispenser unit; determining an amount of printing fluid needed to refill the printing fluid storage chamber via the inlet engaged with said one outlet; disengaging a ratchet mechanism of the dispenser unit so as to facilitate a reduction of volume in the enclosure by a plunger; and engaging the plunger so as to effect the reduction of volume in the enclosure until the ratchet mechanism is reengaged, thereby dispensing fluid from the enclosure into the printing fluid storage chamber. The steps of disengaging the ratchet mechanism and engaging the plunger are repeated until the determined amount of printing fluid is dispensed into the printing fluid storage chamber.