Strengthening Loan Forgiveness for Public Servants Act This bill revises the Public Service Loan Forgiveness (PSLF) program to provide for partial loan cancellation based on the length of public service employment. Specifically, the bill directs the Department of Education (ED) to cancel 15%, 15%, 20%, 20%, and 30% of the amount a borrower owes after 2, 4, 6, 8, and 10 years of public service employment, respectively, on Federal Direct Loans made after the bill's enactment. Under the current PSLF program, ED must cancel the balance of interest and principal due on a borrower's Federal Direct Loans after the borrower makes 120 monthly loan payments while employed in a public service job.