CommonLit does not recommend that teachers recycle old Google Classroom classes with new students. Reusing classes often leads to problems with any website that is linked to your classroom's old students. Instead, CommonLit recommends that you use Google Classroom's Copy feature to make a copy of your old class. This will allow you to copy all of the work created in a class, but you can change the class roster of students in this copied class. For instruction from Google Classroom's Help center on how to do this, please see this article: Copy a class.
Once you have created your new class using Google Classroom's copy feature and added new students, you will need to import this new class to CommonLit. Do this from the Manage Classes page by clicking Create a Class > Import from Google Classroom.
In Google Classroom, CommonLit assignments from your previous class will appear as drafts with no scheduled date. However, when you copy your Google Classroom class and import the copy, CommonLit does not automatically recreate any of these assignments in CommonLit. Therefore, you should not publish any of these draft assignments. You can use these draft assignments as a template for what assignments to recreate in CommonLit and post to Google Classroom, but you will need to delete these drafts from Google Classroom, as the assignment links will not work for students in your new class.