(a) The commissioners shall once a year order the assessors to reassess the annual benefits of protected property in the district if 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) Whereupon, 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 fire protection services benefiting the property change.
(2) If the commissioners determine that there have been no significant changes in improvements on the lands in the district, they may direct that assessed benefits remain the same as the benefits assessed the preceding year.