Your credentials are impressive!
Choose to apply as either a repeat 9th grader or as a 10th grader, and after you get accepted have a discussion about the grade level (but be willing to stick with the grade you applied for). In my opinion this is a better strategy than asking the schools to choose.
I think that your decision about whether or not to repeat should be made considering more than just your chances of getting in. Have a set of reasons that you can explain for your choice so that during interviews you can talk about the topic easily.
I can’t judge whether or not you will be accepted to schools. Nobody can. The pool of applicants changes every year, and you never know what the admissions committee is looking for. Plenty of good applicants get in, but plenty get turned down too.
There are many fine boarding schools, and I recommend that you broaden the number of schools that you apply to. It doesn’t look to me like there is a safety school on your list. In my opinion every student should apply to at least 1 if not 2 or 3 safety schools. You already had the experience of not getting into any schools when you applied 2 years ago, and you don’t want to repeat that.
Good luck!