First of all Alfred, forgetting is a fact of life. So no stress there. I think the really important thing to consider is doing well in your required coursework, first and foremost. My personal advice would be to structure your day intentionally (time-blocking works great), focusing on these core subjects. Then, put aside a couple of hours to "re-learn" the old stuff in a structured way. Re-learning can be a great process to go through, studies find, for knowledge retention. To make sure they stick around longer, I like to use personal backlogs structured this way: 1. Identify: get to know the thing I know nothing about, ask questions, and log my current understanding (spend no more than 10% of your total time here); 2. Discovery: this is where I play with the concept/tool (build stuff, experiment, etc).; and 3. Practice: this is where I apply all this knowledge (usually in the form of small, toy apps that I build and rebuild everyday for about a month to really codify my understanding). Hope this is helpful to you!