There is no "repayment" option for an FSA. There is a "return of mistaken distribution" for an HSA, but that's different.
What you have is called a taxable recovery. You were reimbursed for something that was tax-free, or a previous deduction. The reimbursement is taxable income. It's listed in the "uncommon income" section and it should be called either a taxable recovery or a reimbursement of a previous deduction.
