Dan Larsen and Andrew Conneen do a great CSPAN AP US Government review each year a few days before the AP exam. Larsen is a question leader at AP Government. Above is their 2013 review and here are the other past ones. I will get back to you shortly on the date of this year's live review when your students can call in and get questions answered.
You can watch this year's edition on Saturday May 10th from 9:15 to 10 AM EST on CSPAN.