After you hit the spring, your problem is that you're moving to the right. So dash down to arrest your right movement. You'll hit the spring a second time before it vanishes, keeping you just close enough to the left to dash onwards.
However, I'm stuck at 2700m.
I'm guessing the way forwards is underneath the middle block, but I can never reach the second balloon that way.
I'll be fascinated to see the maximum berry count from this one...