Just so you don't have to do this yet again tomorrow, most epoxies secrete an amine blush when they harden, and if you don't remove the amine blush before applying more epoxy, it will act like a release agent, and you won't get good adhesion.

So, if there are any areas of epoxy that you haven't machined or sanded, and that you want to bond more epoxy to, you should de-blush them by scrubbing with a Scotchbrite pad wetted with water, then wipe off good with wet rags. Sanding also works, but you should also wipe with wet rags (amines are water-soluble) to make sure you get it all off.

Good luck.