I have a form that starts with data of a person, then the form ask some field questions. I want that at the end, the user decide to add another record without refilling the first part again
There are likely several options. Have you seen the Data Collector Workflows section of the documentation? Especially the parts on 'Encounters with known entities' and 'Multiple encounters with the same entity (longitudinal).' The community should be able to help you troubleshoot if you try something from the documentation or have a specific question.