Hey!
I am a reinstated student , and took bio 1a03 2 years ago. My question is, as I don't remember a lot, is it necessary to retake this course as a refresher, or will I be fine to continue on with 2nd year bio courses without retaking it?

I have just taken Bio 2C03, 2B03, 2F03 and 2A03. I think you would be perfectly fine going into these courses after a bio break. You may have to work a little harder to jog your memory, but it shouldn't be a problem. The only course that somewhat built on Bio 1A03 was Bio 2B03 (very little - cell cycle, myosin...) - but just read the textbook and consult youtube! Can't speak for other bio courses though.