Hello,
Welcome to Microsoft Q&A,
To extend the expiration date of your Azure credits in the Microsoft for Startups Founders Hub, you will need to progress to the next level in the program. For instance, if you are currently at Level 2, advancing to Level 3 will grant you additional credits along with more time to utilize them. Please note that this is the only way to extend your credits before they expire.
Please refer to following document: How do I get more Azure credits?
Please note that the only way to extend your credits is to reach the next level before your current credits expire.
Please Upvote and accept the answer if it helps!!