Do you also want to keep the curent state or do you want to rebuild state from scratch?

If you want to create new state, the first option described could work. You just need to start fresh and ignore the current state.

If previous state is important to you, I'd create a new Kafka source with different naming/uid to drink the data. Therefore Flink will understand that as a new piece.

The issue is that Flink does not rely on kafka consumer groups. It relies on its own mechanism of offsets.