Worn out pot tubers that are barely growing are candidates for intensive care therapy . When it is sending up overly skinny sprouts, you need to quit taking cuttings and give it a bit of fresh potting soil and use liquid fertilizer to supercharge it back into health. Not too much fertilizer at first as that would be too much for a nearly dead plant. Time and good lighting or outside, if warm enough, and in a few weeks it will be rejuvenated and ready to be next years pot tuber or planted into the ground. Having said all this some will not make it. 
