If it had died back you can cut the old stalks out and just
compost them. It resprouts from the
root systems. They are rather invasive so if you have issues with them spreading too much dig it out, sink a large pot into the soil (4-5 gallon)and replant it their to restrict the
roots to that one area. I usually just take a few leaves, or I cut the last 5 inches or so. I dry a ton of it for tea and it comes in nearly endless varieties. Have fun.