Try cutting back some of the stringy parts, I wouldn't cut them back more than half way and make cuttings out of them. That way you will have more plants, you could give some away or keep them incase this one dies. That should help thicken up the one you have as it will reshoot.
A man who looks into a collie's eye to receive an icy stare is but a fool. Be at one with man's best friend and through his eyes you will see his very soul.