Reverse Pendulum Long Serve

I have practiced the reverse pendulum a lot of times and I noticed that the serve always ends short and close to the net. It's easier to serve long with the standard pendulum serve because the hand movement makes it possible to snap your hand towards the table net giving the ball enough momentum to make it go long.

However, in the reverse pendulum serve, the arm is going away from the body and parallel to the net, hence it's difficult for me to impart forward momentum to the ball.

Any advice in increasing the momentum of the ball and make it go long in a reverse pendulum serve would be appreciated.