PayPal has a built in security mechanism to stop a customer contract/abonnement after one year. This needs to be renewed by adding payment information again. It is the same step like during the registration process.
Login under https://admin.yoochoose.net which you received after the successful registration process
Then click on the link named "Edit contract data" in the top or if you have a german account "Vertragsdaten ändern"
A new window is opened on the billwerk partner site which is responsible for YOOCHOOSE's payment transactions
Click on "Ändern"
then on "Weiter"
you are redirected to the PayPal site and can renew the payment contract.
Many thanks in advance!
Your YOOCHOOSE Support Team.