Extending a curved line in in-design cs5


Hi all,
I'm having issues with working out as to how I can extend a curved line without changing the curve.

I need to do this to add bleed to either side of the curve and I would like to know if this is possible? If not i'll draw the curve again.
Can't you just merge a rectangle (via the pathfinder tool) to your curve to give you the extra for the bleed
I think Toppers needs the curve extended in case the finishing is off and he still needs the curve to look perfect, rather than it being a simple block of colour that extends the curve -you'd see a section of the block on the end of the curve.

I do this by eye generally as long as the points are smooth and not corner ones.