You are a Machine Learning Engineer at a retail company that uses a DNN regression model to predict customer spending. The model was deployed six months ago and initially showed high accuracy. However, recent evaluations indicate a significant drop in performance due to shifts in customer behavior and input data distribution caused by seasonal changes and a new marketing campaign. The company requires a solution that not only addresses the current performance drop but also prevents future discrepancies with minimal manual intervention and cost. Which of the following strategies is the MOST effective to achieve this goal? (Choose one)