Copper treatment with Cupramine, How do I re-dose with water changes? :O

[George]

I think you need to get a copper test kit instead of using drops as a measurement. Get a seachem copper test kit to go with that cupramine.
Slowly rampping up your copper level to 0.3 and 0.4 over the course of 4 days (longer than the seachem recommendation). Watch your fish carefully for any signs of distress, (not eating, etc.). Not all fish can handle copper treatment. If the fish can't handle copper, there are other methods to treat whatever you wanted to treat. If there is any distress, drop the level to 0.15. Always make sure the fish eating before increasing the dosage. Maintain the copper level over 4+ weeks.
Whatever you do, don't dose any ammonia binding things (like prime) when you have copper in your tank. It will be deadly.
Good luck.