No need to refill it, just check the pressure, if your tank pressure is over 600psi and the outlet pressure is at 100psi you have a different problem.
This could be any number of issues.
I'll take a wild guess and say that you failed to purge the tank of air and properly cycle the carbonator when you initially started it. but then again I could be wildly wrong too!
I don't know if you've read my post on the operation of a carbonator but you might check it out,
http://soda-machines.com/discussions/index.php/topic,12004.0.htmlFollow the startup procedure in my post and make sure the carb cycles at least 4 times. Cycles means starts and stops, it looks like you have a small McCann's carb so it should run about 3-5 seconds and then stop as your drawing from the fountain.