I think it's Ti plant (Cordyline fruticosa.) If so, it would do better if the soil is kept consistently moist. How are you determining that the soil at the bottom is dry?
This would be easy to repot, just pull the whole thing out, chop off the dead stem, and if you find a root pie at the bottom, chop that off, knock off the rest of the soil, and it will probably fit back in the same pot, with new soil. The surface of the soil when you are finished should be at the same level, with the plant not any deeper or sticking out farther than it is now.
