Beginner Gardening: how to save this dying tropical plant?, 1 by youngman

youngman wrote:
i used have this plant which i just grow in the water, here is a picture.

http://davesgarden.com/community/forums/t/892417/

in the other forum, someone told me that it is called "Dieffenbachia amoena.", but from what i see at homedepot, those plants' leaves look dull, the one that i have has shiny, oily looking leaves.

anyway, i have transplanted it to soil a while ago, then during the winter, i decided to give it more sunlight, i put it outside, then it started to die.

now that is all that is left. the stem just somehow dried itself which i already cut. this pot is made of porcelain. the stem that is left used to be green, now it is turning brownish green.

I am thinking about taking it out, and replace the original soil with the compost soil? should i do that?