Sidehops, sidehops sidehops... That's the only thing I can think of right now. :D I've tried to improve over the last couple of months but whenever I fell off the wall I left that technique out of my practices for quite some time. Now I will focus on this a bit more and force myself to do like my 2 1/2 year old son does. He falls, stands up and tries it again (no sidehop obviously). 

So here's my status quo now. I still have to put more force into the pedal kick when going up and preload a lot more. The vertical I have, it's the technique that's needed to get up onto higher walls. Also, I'll need more flexibility for the tucking part up there so I will concentrate on that as well. 

The wall in this video is the highest I can do for now but I can already see myself improving a lot if I manage to keep at it.