You can check the approximate ink levels from the computer.
You can continue printing while the ink low message is displayed. Replace the ink cartridges when required.
Continue Printing Temporarily without Replacing Ink Cartridges
Continue Printing to Conserve Black Ink (for Windows Only)
It is Time to Replace the Ink Cartridges
Checking the Ink Levels - Windows
Checking the Ink Levels (Mac OS)