You can't refill these cartridges unless you have a chip re-setter. The chip measures how much ink is used and when IT decides the cartridge is nearing empty it warns you to replace it then stops the printer from printing. You can refill it but you need to reset the chip with a re-setter or it won't work.
The software provided by Epson is for Windows and includes the ink level reporting facility. The Kubuntu version obviously does not include it. Some others who are more into Linux than me may have a better answer on this point.