Myriam,
You could also force it to go dormant, & treat the risome. That way you could get rid of the old soil, treat the risome while it is dormant, & in a few weeks start a new plant.
I am thankful of my location. It makes this kind of problem rather easy to deal with. In this environment we have to take measures to control the growth of these plants. Some of the plants here are incredibly monstrous. I have an EE now with 2 foot long leaves in my little space, & it is only getting bigger. This is only 1 season of growth also. This plant started out with 6 inch long leaves when I arrived in Colombia back in September. I also collected another this week to replace 1 I sold that has a risome a foot long, & weighs probably 7 or 8 pounds. The leaves on this thing are huge too.
