Renewing the Developer Program Membership after it expires
You may renew your Developer account whenever you want. Just keep in mind: All your 'live' apps in the App Store will go offline when your membership expires. When you renew the Developer Account you can bring the apps back to the store again without setting up / needing a review proces.

I had the same with a customer of mine, their membership expired for several months (they just didn't care enough) and they renewed the account without any hassle.