In addition to other useful answers... this sort of problem will recur forever, since students (even with good attitudes) chronically misjudge the importance of background courses, and chronically misjudge the degree of facility and competence really desirable for later work. E.g., sometimes students see a passing grade (C+?) as showing they're ready to move forward... while, in reality, that's terrible from the viewpoint of competence and reliability.
But there'll be no room in your course to rant about the failings of the ambient cultural attitudes, blah-blah-blah. Nor will many students be willing to agree with the premise that they in fact do not know things they thought they know... with "know" as certified by a grade in a course in the past.
Thus, for me both in undergrad courses at all levels, and in grad courses, I "recall" things ... sometimes in gruesome detail ... pretending to be apologetic for boring people who know it all too well... to at least passively drill everyone in the absolutely critical riffs.
Yes, I am implicitly doubting that formal reviews are as effective as one would want, exactly because of the inaccurate self-perceptions of the students. It is quicker, and not toooo burdensome to "in-line" the review/recapitulation of things that... yes, we'd like to be able to assume the kids know, but they just don't.
The meta-comment is that this is a huge issue, and we can't expect any sort of "solution", but only a strategy to fight back on an on-going basis...