When revisiting topics for refreshing their UPSC knowledge, candidates should prioritize conceptual clarity and focus on the most crucial themes. It's beneficial to review **class notes**, summaries, and previous year questions to reinforce understanding. Engaging in discussions with peers or study groups can also promote retention and provide different perspectives. Identifying and filling knowledge gaps is essential, along with regular self-assessment through mock tests. Finally, ensuring a balanced approach that incorporates both revision and new learning can enhance overall preparation.