The cold-start problem remains a significant challenge in recommendation systems based on generative models. Current methods primarily focus on enriching embeddings or inputs by gathering more data, often overlooking the effectiveness of how existing training knowledge is utilized. This inefficiency can lead to missed opportunities for improving cold-start recommendations. To address this, we propose the use of epistemic uncertainty, which reflects a lack of certainty about the optimal model, as a tool to measure and enhance the efficiency with which a recommendation system leverages available knowledge. By considering epistemic uncertainty as a reducible component of overall uncertainty, we introduce a new approach to refine model performance. The effectiveness of this approach is validated through extensive offline experiments on publicly available datasets, demonstrating its superior performance and robustness in tackling the cold-start problem.