How to efficiently fill in the gaps after on year without any math

I am in an unusual situation where I completed my first uni year as a math major and had to go on an academical leave for health issues .

I’m starting my second year in a few days and frankly I took a peak at some of the material and I can clearly see I forgot a lot of the stuff from my real analysis classes which r heavily used here and there in my new courses ,even tho I passed my first year with high grades I feel like most of my knowledge and dexterity with proofs is lost .

The main crucial classes that come up a lot in my new courses are real analysis, multivariable calculus and some linear algebra .

If anyone went through smthg similar I am really in need of advices on how to tackle this year , filling my gaps and avoid being lost in the process and not doing enough in my current courses .

Even if this never happened to you , how would u proceed if u were in my shoes , to eventually still get decent grades so that I don’t ruin my gpa ?