you have start ignoring input, right?
but now you want input to not be ignored?
You could probably just use the normal jump, as it seems the platform is on the floor..
You are already using the vector x to make it slide, so I gues changing the vector x wouldn't do anything but slide faster (or slower)
You could add a small Y vector to your jump, else the "gravity" will have the player back on the floor before you know it..