You sure can! You can exchange your existing cylinder for the SodaStream Quick Connect Cylinder as long as they are not used and with the plastic seal on - at a retail location which carries them or on our website.
Check out the following compatibility charts:
Sodastream Sparkling Water Makers compatible with the Sodastream Quick Connect Cylinder
Sodastream Sparkling Water Makers compatible with the Sodastream Screw-In System Cylinder