Where do you have this plant? Is it getting enough light. Is the stem discolored--red or black just above the soil? Does it have red in the leaves? Is it still in the soil it grew all last summer? Have you fertilized it at all?

If it's not discolored you can rule out disease. What I would do is transplant it into fresh soil and give it a shot of diluted fertilizer. When you have it out of the pot, have a good look at the root--does it look healthy? Is it all tangled and twisted together--does it go round and round at the bottom. These is a sign that it is root bound. Untangle and straighten out the roots, even if you break the odd one. When a plant gets root bound it can't take up any nutrients and the plant will die or do poorly.

When you've done all this then give it the best light you can and wait for new shoots to form. Then you can give it a haircut to make a nicely shaped plant, but right now the plant needs that one shoot.

If it is root bound, make sure you put it in a bigger pot