There are 2 options that I'm aware of:

a) The free "K2 Import / Export Tool" from www.individual-it.net/en/Joomla/ (scroll down a bit, it's the 2nd extension) - but I'm not sure if it's updated anymore, however it *should* work. Attached here for your reference: jmp.sh/ZzMOSbH

b) The commercial "RO CSVI" from rolandd.com/products/ro-csvi (which may offer more features).