The analogous 'market' financial model I fall back on is this: the P/E expansion of a growth company, when the company introduces something 'New' that triggers renewed investment interest.

I would take meticulous notes and documentation of ALL the issues...dates etc etc.... and not renew her lease.At the MINIMUM I would give her an ultimatum ....no more conflicts with the neighbors...no more late or partial payments....no issues with maintenance of the property....and make her M2MAnd the model tenants should just go about their business and ignore the lower tenant

If I were in your shoes, I'd give notice to one of the tenants that I was not renewing the lease. 

Rent is $1950 (we just increased it a couple of months ago when the lease was renewed), and we've had only a single tenant.  

YOU still have to give proper notice,, NO way can you do this the way your thinking,,Download your state landlord tenant laws so you can operate this business properly,Get a copy of their current lease,, IS there a clause that says,, it will automatically revert to a month to month term if not renewed for a longer period..IF so your fine,, you'll just give them notice of lease terms changes the next month,, they don't need to vacate if you want to keep them,, you can give them a heads up what the terms will be, you can suggest it would be nice to start off with a new lease, but understand they have a month to accept that new lease or give proper notice to vacate..It's not that it can't be done,, it has to be done the proper way..

@Connor EichmanThey stoped mailing out renewal notices in Philly (I got non this year).

One of remaining units is coming up for renewal and I am doing a rent increase of $50.00 and I will rent the other two for the market rents ($75.00 higher then previously rented for).  

Typically if they have plans to move they will not want to spend any money on the space in the short term.Howe far in advance do they have to give notice to renew the lease before exercising the first option period?

Next thing you know, it's time to renew their license but money is tight because they just bought a new truck, had another baby, took a trip to Cabo . . . fill in the blank.I don't see it as a chicken-or-egg question.

In this case one lease just renewed and the other is on a two year lease.