When is the best time to refill my inkjet cartridges? Customer Service Updated April 01, 2019 17:27 If possible, you should refill your inkjet cartridges before they run out. This will prevent ink from drying in the print head between refills. Related articles How do I use a refill kit? How many times can I refill a cartridge? Can I refill a toner cartridge? What are inkjet refill kits and how can they save me money? Will you refill my old printer cartridges?