Complex sentence: Additionally, the "High School Program at Princeton University" permits qualified juniors and seniors to take free courses at Princeton University if they have exhausted all high school course alternatives within a discipline, receiving only high school credit for any university courses successfully completed.
Split into simpler sentences: Additionally, the "High School Program at Princeton University" permits qualified juniors and seniors to take free courses at Princeton University. Students must have exhausted all high school course alternatives within a discipline and receive high school credit only for any university courses successfully completed.