First of all, that hair is breathtaking. 'o'
Secondly, I think of "refinement" as developing a general consistency. For example, being able to draw a hand correctly ALL the time, instead of it being hit or miss depending on the drawing/pose. Or in the case of a single picture, being able to draw ALL the body parts correctly, instead of drawing good-looking hands but lopsided feet, or super-detailed eyes on a lump-shaped head (common anime artist mistake).
In the case of this picture, I might guess the comment referred to the disparity between the drawing of the person and the drawing of the person's clothes...they differ greatly, both in level of detail and even line width. It almost looks like they were photoshopped together from two different drawings.
And if that wasn't intentional (i.e. the shirt isn't finished or something), then yeah, some refinement could be in order.