Plotting help!?

Okay, writing friends I need your help.

I am generally a plotter, but my current Middle Grade WIP is behaving more like a discovery/pantser project. Every time I make a plan, the Characters choose a different path, that is ultimately better than my plan.

I’m 15 chapters in at about the midpoint and struggling how to get myself to the climax.

I’d love any pantser tips to keep working and ramping up the tension as you head toward the climax. I know where I want to go, just don’t know how to get there.