People’s data practices and their supporting personal informatics are imbued with a wide range of concepts of value that are central to their data imaginaries. They inform how individuals adopt particular products and services. This elusiveness of value creates a challenge for designers to gauge users’ value preferences, which are personal, contextual and abstract. We propose deliberation as a process to operationalise design for elicitation, reflection and value formation, using Live Action Role Play (LARP). The paper demonstrates how our deliberative LARP precipitates the otherwise ethereal data values to unfold in a social setting. We argue that engaging people in reflecting on and playing out their own value formation offers designers more powerful insights to address complex challenges of data-driven societies. We report on our findings that agency and negotiability are key to transcend the politics of preferences in data practices and thus enhance acceptability.