What type is it? Static or adhesive?
I had several pieces of dust/debris under my Static screen protector. I carefully pulled back from different angles and used a piece of scotch tape to pick up the pieces. Because the screen protector is staticy, the debris didn't sit on the glass, which means I did not have use the tape on the glass. After removing several pieces, I resmoothed out the screen protector and it is completely unnoticeable on the screen now. Forget the people that say you don't need one. Sure the glass is very durable, but everything has a breaking point and accidents happen.
If your screen protector uses adhesive like the Zagg ones, this advice obviously won't happen. disclaimer: this advice is not guaranteed to work, avoid touching the tape to the glass, but rather just try to touch the backside of the screen protector while you pull it back carefully.
EDIT: mcdj beat me to it. Takes a bit longer to type out long messages on the iPad