How does a reapplicant handle LORs?

If an MD applicant for this cycle has no success, and reapplies summer of 2018, does he fill everything out again and does he have to resend LORs or can the existing ones be reused?

The optimal way to handle this is to ask to the recommenders to “freshen” their letters and resubmit them.
A freshened letter is the previous letter with a new current-year date plus any new accomplishments, activities, improved GPA etc that the applicant has achieved in the past year added.

Alternatively, it is acceptable to re-use last year’s letters, though some medical schools specifically say LORs must be “current”.

AMCAS’ letter service does not hold onto LORs from previous cycles so no matter whether the applicant is using freshened, new or old letters, the applicant has to resubmit them to AMCAS when he opens his application for the next cycle.

Thanks