We present a script for conversational reflection guidance embedded in reflective practice. Rebo Junior, a nonadaptive conversational agent, was evaluated in a 12-week field study with apprentices. We analyzed apprentices' interactions with Rebo Junior in terms of reflectivity and measured the development of their reflection competence via reflective essays at three points in time during the field study. Reflection competence, a key competency for lifelong professional learning, becomes significantly higher by the third essay after repeated interactions with Rebo Junior (paired samples t-test t(13) = 3.00, p = 0.010 from Essay 1 to Essay 3). However, we also observed a significant decrease in reflectivity in the Rebo Junior interactions over time (paired samples t-test between the first and eighth interaction: t(7) = 2.50, p = 0.041). We attribute this decline to 1) the novelty of Rebo Junior wearing off (novelty effect) and 2) the apprentices learning the script and experiencing subsequent frustration due to the script not fading over time. Overall, this work 1) informs future design through the observation of consistent decreases in engagement over eight interactions with static scaffolding, 2) contributes a reflection script applicable for reflection on tasks that resemble future expected work tasks, a typical setting in lifelong professional learning, and 3) indicates increased reflection competence after repeated reflection guided by a conversational agent.