A person having a property in a area suffering with high vacancies. The property has 4 portions of which 2 are?

A Person has a property in a area plagued by high vacancies.There are 4 portions out of which one is leased out XYZ co. whose lease term ends at the end of year and another one leased to other firm which extended its lease period for another 2 years at amount lower than previous agreement. The person has hired a broker to fill up the other two vacant portions. Suggest him how to retain the existing tenants, and how to attract other tenants for vacant portions, so that he earns profit without incurring loss?