Bamboo - Wind Scorch and Root Bound?

Hi!

I've had this bamboo for a number of years now and is looking rather tired. I fear it may have gotten wind scorched and perhaps is getting root bound in this pot. 

This is the largest pot I can get, so I can't really re-pot it, but any thoughts on how to revive? I could possibly remove it from the pot and cut it in half, but the tapered top of the pot and strength of the bamboo shoots will likely make that difficult!  I haven't seen any new shoots coming up yet this year, but there are small new green leaves on these existing stalks. 

Thanks!