Knowledge workers increasingly rely on conversational AI for sense-making tasks (e.g., conducting market analysis), yet must repeatedly reconstruct context and intent to meet their goals. A formative study (N=10) showed that workflow reuse with AI often failed. Current tools either only remember preferences or enforce rigid, predefined workflows—neither adapts to evolving goals. We present ThinkFlow, a system that maintains a dynamic common ground through a cognitive workflow schema, enabling users to express intent and AI to adapt and reuse workflows across contexts. An expert-rating study shows that the schema can accurately capture the collocutor’s reasoning process, and when reused for a similar task, improves the AI’s responses compared to when the schema isn’t present. A user study with eight knowledge workers demonstrates that ThinkFlow supports awareness of evolving workflows, intent expression, and flexible application across contexts.