If they have a lease, then they can stay until it's expired.

Making contacts, calling FSBO's, expired listings, hosting other agents open houses, joining local chambers to network, attending networking events, etc.  

Text, email and send her a letter to remind her that by law she is responsible for paying the rent on time until the lease expires.

Each property has a fire extinguisher with the expiration date noted on the outside of the can with a Sharpie pen (those suckers expire!). 

Every other place I've rented I've signed another lease before the first one expired.

I understand that an IRS lien would expire October 2020 (10 year limitations).

Interesting Update: Their current lease doesn't expire for another 6 months, and I haven't even discussed renewal with her, but she contacted me today to ask to renew their lease for another year (only four days after telling me this information).

My plan is to kick them to the curb when the current leases expire, the first one isn't til June.

Only use the MLS to get an expired listing.

As long as your financial snapshot in time remains accurate and you aren't marginal, I generally don't put explicit expiration dates on mine, for what it is worth.