You should have two options here.
Option 1: You will have to wait until the start of your next monthly billed period when the subscription will be reactivated automatically and the monthly credit replenished.
"Azure subscriptions with credit such as Free Trial and Visual Studio Enterprise have spending limits on them. You can only use services up to the included credit. When your usage reaches the spending limit, Azure disables your subscription for the rest of that billing period. Your subscription is disabled to protect you from accidentally incurring charges for usage beyond the credit included with your subscription."
Option 2: Add a credit card to your account and use this to pay for the additional costs incurred: https://learn.microsoft.com/en-us/azure/cost-management-billing/manage/spending-limit#remove-the-spending-limit-in-azure-portal