You could adopt or adapt some of the following motivational inputs:
- We appreciate your contribution and look forward to you taking on even more challenges in the future.
- You have done an excellent job, and we are sure you will do an equally good job with the new responsibilities being assigned to you.
- We are confident that with this promotion and growth, you will take on the leadership mantle and do justice to the trust reposed in you.
- We are sure you will continue to exhibit the same level of insightful thinking, proactive leadership, and extraordinary performance in the coming year.
Trust my suggestions trigger even more ideas for you to explore.
Regards