Will I need to reapply every year?

No. If you do nothing, your current plan will continue. However, because both your plan and your medical needs change from year to year, it is important to re-evaluate your Part D plan every year to make sure you are receiving the best coverage for your needs. By September 30 each year, you should receive the Annual Notice of Change from your plan. That letter will explain the prescription drug benefit and formulary (the list drugs covered) being provided in the coming year, as well as any changes to premiums, copayments and coinsurance the plan has made to the coverage it provided in the current year. You should review this notice to make sure your prescription drug plan still meets your needs.