In Trailbreaker – Rolling Sky Ball game, force to the jump does not add instantly. When you press jump button, next third of the second (or less) force would be exponentially added, always against ground (track).
Means, if you want to perform longer jump, be sure you have just a bit of enough track in front of your Jupiter.
When you need longer jump, please resist temptation to jump from the very edge of the track. Once in the air, if there is no ground/track below to add force against it, your jump will be short.
Practice. It is not so hard.