There are a few scenarios to why your referral program would become disabled, such as:
Kickbooster is no longer connected to Google Analytics (Crowdfunding)
Your store is not live (Shopify)
You disable your referral program
If you didn't disable your referral program, you will receive an email notification advising what caused your referral program to become disabled and the necessary steps to fix the issue. After the issue has been fixed, you will need to reactivate your referral program as it does not automatically reactivate.
Reactivating your referral program is extremely easy! Just head to your 'Activate' settings, change the toggle to 'Yes', and hit 'Save and Continue' (This applies to both Crowdfunding campaigns and Shopify stores).