depends.
if its a stand alone job sometimes i just dont go back and strike them off and move on.if they phone up months later i just explain the reason why im not coming around anymore.
others that are right near other work a quick matter of fact explanation usually suffices.
sometimes with late payers its because their so busy or work abroad so i try and get them to pay online 6 months in advance.quite a few of my customers do this now that id be forever chasing up previously.
others are struggling financially so get suspended until things pick up for them.others just dont wanna pay so get dropped for good.