(a) The commissioners shall one (1) time a year order the assessors to reassess the annual benefits of the district, provided there have been improvements made or improvements destroyed or removed from one (1) or more tracts of land in the district, making it necessary to have the annual benefits revised.
(b)
(1) It shall be the duty of the assessors to reassess the benefits of the district, and the annual benefits assessed may be raised or lowered as conditions of the property change or as requirements of the fire department change.
(2) However, the annual benefits extended against any piece of property shall not be increased from the annual benefits originally extended unless the original benefits were uniformly assessed against all classes of land in the amount of one dollar ($1.00) per parcel of vacant land and ten dollars ($10.00) per parcel of improved land and providing there have been material changes in value or character made from one (1) or more tracts of land in the district since the original assessment of benefits, making it necessary for the assessors to equitably reassess the annual benefits.