Do you know if the price has a chance of going up? Or is it time to sell?
If you are holding and already made a (non realized) loss, hodl, it should come back up in a matter of two or three quarters if bad news don't keep stacking up.
If you are looking to buy more, get ready but remember: don't try to catch a falling knife. As far as any one can tell, it could go back as low as before the China rally started.