My chainring bolts keep coming loose... I have to tighten them every other day and I'm just riding my bike to and from class every day. What can I do to stop them from coming loose all the time?

The bike is a Motobecane Track with the stock chainring and cranks.

The cycling team here is having a bike repair fundraiser, so maybe I'll stop in see if they can fix it. My bottom bracket also needs a good lubing, anyways.