Please understand.
–There is no necessity to volunteer at all even for Ivy League Schools.
–There is no necessity to volunteer at one place to show dedication.
–Even with that said, college admissions officers will see that you moved and will understand that you could not continue to volunteer at the same place.
–And also recognize that unless you are the child of a huge donor or a recruited athlete, that admission to Ivy League and equivalent schools is pretty much a crapshoot. You really should extend your definition of what schools you will target