Recommendations for books that present high school mathematics more rigoously?
I can understand you want to "shore up" what you already know, but most of the time the solution to this problem is to go ahead and learn newer more advanced things. It is better to be exposed to more things.
You will have plenty of opportunity to review the old stuff as you go along, and you will probably get a better perspective on it as you see it in more advanced settings.
A good reason to avoid reading material written at a highschool level is that a lot of it is organized for the awful curricula in place at high schools. That means it is almost by definition pedagogically bad. (Don't get me wrong, I realize there are exceptions to my complaint, but most of the books are bad.)
Case in point: highschools think "rigor" is teaching two-column proofs in geometry, when actually that is a fantastically boring and overly formal way of doing things that mathematicians would not dream of doing in daily life.
Try Basic mathematics by Serge Lang.
Here is a great book for you. It was written by one of the outstanding mathematicians, expressly for students in your situation:
http://www.amazon.com/Algebra-Israel-M-Gelfand/dp/0817636773
It is intended that you can understand it and open your eyes to the world of math. Good Luck.