Except as otherwise provided in this chapter, nonconforming structures may continue and may be maintained, repaired, altered and expanded, provided that no increase in the nonconformity results, all other applicable regulations are met, and the cost of such maintenance, repair, alteration, and/or expansion, when expressed as a percent of replacement cost of the existing structure, shall not exceed in any twelve (12) month period the percentage shown in the following table for the applicable zoning district and project type, unless a conditional use permit is obtained.