You could cut all the way back to the trunk and start again. The question is whether that will give a better result?
For some reason all branches only have a few leaves right at the tips. That could be due to not enough sun, starvation, too much or not enough water or some pest or disease. Hard to tell just from photos and no real background.
Any tree will respond to pruning better if it is happy, healthy and strong. maybe concentrate on building up strength this summer before doing anything else.
If you can get it strong and healthy I would probably cut all the long branches back hard and rebuild the branching. Maybe not all the way to the trunk but mostly quite hard I think. Then look for a style to follow when you know what branches have responded best.