Can I reuse experience hours towards my next credential?

Yes. Experience hours are cumulative, so you can keep building upon them until you reach the experience requirements for the next credential level.

For any credential, you can count coaching experience hours from the start of any 30-hour (or more) coach-specific education program that had at least 24 hours (or more) in Core Competencies training.  

If you actively keep track of hours on your client coaching log. Before you know it, you will be ready for the next credential level.