Often there is a residual debt left after the fixed interest rate period, which you still have to pay. Don't worry, this is quite normal. The follow-up financing determines the interest rate at which this residual debt will be repaid.
There are different types of follow-up financing in Germany: the rollover with your own bank, and the debt rescheduling with another provider. In addition, in some cases, you can opt for a forward loan to secure a low interest rate.