So far my Liu Kang high combo still works and is pretty damaging. I believe it is about 21 to 22 hits. You will need to have his Low Fireball to get the last hit.

3, 3, 3, Dash Forward, 4, 4, 3, Bicycle Kick Amplified Twice, Low Fireball

The Low Fireball must be thrown as soon as the opponent is knocked to the ground. If timed right it will hit them right as they try to get up and the game gives you that last extra hit.