Does naybody know of any way to extend an area fill?

I have created a filled area using the line tool, as it isnot a closed shape i cant use the Area fill tool. I now need to extend the the area that is filled. I know if I double click on the filled area I can get the grips up to adjust its position, but what I need are more grips!

I suppose it would be like the 'edit vertex' section of the PEDIT command if i was in AutoCAD.

Any help much appreciated as I dont want to have to recolour the area.