Maybe they don't take care of the property, or have lots of pets that cause extra damage.

Do you have a pet policy which explicitly states that which should be common sense ... i.e. you are responsible for your pet, its behaviour, its waste and any damages it causes?

If she seems like she fits your rental criteria, I would say renew her lease with a thorough contract that outlines rent payments, pet policies, maintenance, etc. 

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

I do a mix of both refundable and non-refundable, taking a full month's rent as a security deposit, plus a non-refundable cleaning fee + pet fee (if they have pets).

During the interview we talked about no pets and it was written on the one year lease.

I would also make sure to mention that since the tenant is choosing to not operate the hvac system they will be responsible for any damages that occur as a result.Bear the storm until move out but be prepared for any petting work requests that result. 

A broken fridge, an unauthorized pet, or a 19-year-old girl that just found out you won't be giving her the entire deposit back. 

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

One of my questions was and always is "do you have pets" as we do not allow pets or animals in any of our units (this is stated in the advertisement).