What do I do if my Recepisse is about to expire and I still haven't received my carte de sejour?

I am not aware of any way to check the status of your application online. It might be worth trying but I wouldn't expect too much from a call either. In all likelihood, a decision hasn't been made yet. You will hear about it whenever there is a decision but that doesn't solve your immediate problem.

Meanwhile, you are supposed to show up/make an appointment (depending on the préfecture) to renew the récipissé. It's very frustrating and is supposed to be exceptional but in practice it does happen a lot.