No need to drain. What's done is done. You can live with the copper....or add a metal sequsterant to deactivte it. I personally would live with it. If you shock and the water gets greener it is the copper. You will need to add sequesternt then. A lot of times that doesn't happen. A lot of times it does.
Just keep tabs on it. It will help kill the algae.
If anyone gets green hair from the copper in the pool it is easy to fix....check out this thread!
http://www.poolforum.com/pf2/showthread.php?t=326