How to say the renewal fee in Japanese? . . . . . . This worries me.

Renewal fee-refers to the subsequent payment of prepaid services such as prepaid cards.

Early repayment is not common in Japan, so there is no corresponding vocabulary. It can only be expressed in other ways.

Prepayment method = プリペィド type

Renewal fee = depends on why you renew the fee.

For example:

Update the phone fee-プリペィドほのカードをぅ.