Can I Get A Higher Score?

Hi, I’m an incoming high school sophomore and I’m retaking the ACT this Saturday. I recently finished my freshman year at my local public high school and have accepted a position at an elite boarding school for the remainder of high school. So far I have only taken basic courses at my high school, but I will be in much more rigorous classes come the beginning of the fall semester. I have taken the ACT twice.
1.) June 2014- end of 8th grade and my scores were
Composite:25
English:26
Math:23
Reading:26
Science:24

I took it a second time to have a better chance for admissions to the boarding school
2.) December 2014- 1 semester of normal high school classes
Composite:27
English:27
Math:22
Reading:31
Science:26

I have been preparing by using an ACT Prep Guide Book(Red Book) and I have seen some improvement (26) on my math scores, but my reading(29) and science(25) scores tend to go down. I know that I shouldn’t stress about the ACT right now but I will be using my scores for placement into higher level classes. I would appreciate any advice about if it is possible to improve my scores? I’m hoping to reach 28-29 this time.