probably identify what exactly you forget , is it dates , numbers , whole theories or specific keywords?
This should lead you into identifying what to do , if its keywords try to connect it your theory , remember the first letters specifically.
if its concepts of applications start making questions out of the lesson material especially the parts which you summarrised (im assuming is the most important part of it)
if struggling with concentration during studying or during exam , make sure to get alot of sleep and start studying wayy before hand so you can study in smaller sections (also allows multiple revisions). Dont waste a lot of time rewriting things if it doesnt help you remember things in the long term , instead read it and understand and try to connect it to the rest of the lesson.
Identify examples is also a good way of ensuring you understand and can use it as a placeholder to remeber the theory