I am having the same problem, so I worked up the the hard soil with fingers.. Very hard not to upset the roots.. I added more soil and perlite (pre made mix). My pots are large and i kept mine in these pots since babys.. I have heard that this is not good for the bitch. Because the nutes in the soil breaks break down..

I was using Canna Terra Flores, i am now using cannazym and the flores and a booster.. Canazymis supposed to break up dead roots.. I should have used this earlier... Maybe, i have not seen them perk up yet, so the Jury is still out.. Let you know..