Dependent on whom you are certified through, or with. If you are NREMT, one can obtain up to ten hours through internet, video, magazine articles. If you are in military branch, if you are attending courses that meet the NHTSA/DOT curriculum, you can have your training superior write a letter of hours/speakers/topic that your regular T.O. can authorize. The other option is to attend a conference, and obtain CEU's through it, or another local EMS service.
The difficult part will be locating a refresher course if needed.
R/r 911