Pays late every single time, driving me crazy

[Katherine S.]

We have a tenant in one of our SFH, moved in last December, and has paid late EVERY SINGLE TIME (with the exception of the first month.) He pays the $50 late fee without complaint. He asked to move his pay date from the 1st to the 15th, and we agreed, and then he was late on that (1 1/2 month's rent). We have started to file 7 day notices at the first possible moment, and he pays at the last possible moment before we file to evict.

I don't have any language in my lease agreement about habitual late payments (a mistake I am correcting now.)  Is there anything I can do about this except grit my teeth and not renew him when the lease is up?

What can I do to prevent this in the future?