We have a thread discussing the effect of the government shutdown on Global Entry applications processing timelines. Most of the information there should be applicable to renewal applications.

As long as you put in your application for renewal before the expiration date, you will continue to receive Global Entry benefits for six months following the expiration date pending conditional and final approvals.

Sorry, I'm in flight and on my phone, so I'm unable to readily post links to the other thread and the relevant DHS web page.