I would welcome mandatory refreshers every 5 years. Not just because people forget, but also because the best practices (legal and medical) can change over time and people should be kept up to date.
In California, DMV requires renewing the drivers license every 5 years, which requires a simple vision test and a knowledge test about the rules of the road. The knowledge test can now be substituted by a ~90 minute at home online training (short videos and quizzes). I think that would be a great model for first aid refreshers as well.
I mean, personally I would like to see a behind the wheels test every 5-10 years too. I know too many people who I think are entirely incapable of following the most basic safe driving rules (like checking blind spots when changing lanes, buckling up before starting to drive or yielding to pedestrians when exiting a parking lot). But such a law would probably be deeply unpopular with the population.
Same in slovenia... but do you ever have to renew it? Or do you pass it at 18, and then forget everything in the next 10, 20, 30 years?