Long time tenant issue

[Sarah Byun]

I'm new at this so that any advice will be appreciated.

The first triplex we purchased had long-time tenants.  This particular tenant's been there for almost 20 years, and the rent didn't increase much since the first time she moved in.  After purchasing the property, the lease ended, and every tenant agreed to sign a 2-year lease.  We increase this particular tenant's rent by $75 since this tenant is still paying low rent.  A few months ago, we found out that the floor this particular tenant lives in does not have a separate electric meter; we ended up taking over the electrical bill.  (That's another issue that needs to be resolved, and I have to figure out how to go about that)  We dropped off the new lease beginning of April, and the old lease ended in May.  She refuses to sign the new two-year lease of $75 increase and tells me that once the lease ended, by law, she is month-to-month. I returned the rent check and asked her to either sign the new lease or leave verbally.  Technically, I can raise her rent since we have not rent control here in the state of PA with a written notice, right?  So I can send her a written month-to-month increase rent letter or vacate the property in 30 days.  Is this right?

Then how do I go about the rent for June that I haven't received?  Since I didn't clarify to her, should I ask her to pay the old rent in June and send her an official month-to-month rent amount?

Is there another better option?  

This tenant does ask for little minor things time and complains a lot, but we don't know if we want to lose a long-term tenant who hasn't been missing a rent.  But by cleaning out the place, I can raise the rent and find a new tenant, but that is another headache I might be putting myself into...

Any thoughts?