If state law requires landlord to mitigate damage cause by early termination, it usually requires such mitigation to be carried out in "reasonable effort".
Reasonable effort means landlord should do everything he should normally do to rent out a unit, like advertise, check background, etc. Landlord need not to use "heroic" effort to rent out the unit, such as lower the rent, lower qualifying standard etc.
So I would think the reasonable effort includes renting out a unit AT market price. The market price could be higher than the price of last lease signed 12 months ago. So as long as you have evidence showing the market price is what you are charging now, you should be okay.
Evidence could be anything, Zestimate, similiar listing of simliar property nearby, etc. You have the burden to produce those evidence, and the other side could rebutt, we will worry about it later.
