I just received an email from Apple telling me that my "Apple Push Notification Service Certificate will expire".
Generally, you can simply go to the Apple Developer Portal, create a new push certificate and upload it to Pushwoosh (you don't have to rebuild or update the application). You can find the details of how to create a push certificate in our iOS configuration guide:
Moreover, you can use our Auto Configuration Tool in order to renew certificate:
Note that any existing APNs certificates for this Apple App ID will be revoked during Auto Configuration!