1 - we are on the wait list for one of the top boarding school, does anyone know if we need to reapply again next year if we are still waiting for the spot and do we need to take the ISEE again ?
2 - can anyone share with me what 8th or 9th graders should do in summer ?
You have to reapply. Whether or not you have to retake standardized tests is up to the school.
Thank you
Just because you were waitlisted this year doesn’t mean that you are still on the waiting list throughout the next year application time periods. You will have to reapply the same way as any other applicant if yo want to get into that school. If you do not get taken off the waitlist for this academic year (2015-2016), then its just over. The waitlist doesn’t continue.
Summer: You could do a camp sponsored by the top boarding school you wish to attend, just to get a better feel of the school. Or just do a lot of volunteering. I found volunteering a lot more helpful than going to elite camps.
I was waitlisted at a boarding school this year too…I guess we are going through the same stress each day…unless you were already taken off! In that case congrats 
There are many things you can do this summer. Do something that you like (and no that does not mean you should stay home and play video games all summer).
There are many different camps, travel programs, volunteer opportunities for 8th & 9th graders. Some day camps start CIT programs at 14-15 too.