With Subscribers, you can create a recurring notification that allows you to subsequently send a push notification automatically

To set up a recurring notification, log in to your Subscribers.com account dashboard and navigate under  "Ecommerce"(If you're using Shopify)> Recurring Notification menu or "Notification" (For any other platforms)> Recurring Notification.

Now you'll be redirected to the page where you'll be creating your recurring notification which is really straight-forward.