When creating a new recurring invoice and adding a line, using  Product Lookup feature will make it easier. It will enable you to browse your org’s existing products per pricebook. However, there will be instances that clicking on the link does nothing. This problem is caused most of the time by your browser blocking the pop-up window where you can  choose the product/s from.

To resolve this, just simply allow the pop-up window in your browser as shown in the image below.