Okay wait hold on.
Are you saying that your previous videos have more views than the later of the videos because the videos you have now have not received as much attention as of the previous to the last videos?
More than likely you probably had some sort of TAG or name of title that caught someones eye and they did not sub to you or wanted to come back I guess.
That or promoting one video
To gain back those views you just have to make content you believe people will come back to and what you will enjoy making I guess.