Chestnut Hill 4: Playing for Keeps by Lauren Brooke

Welcome to Chestnut Hill, the school for girls who love riding!
 
Lani has always been a top student but all the time she spends riding means her marks are suffering.
 
When her parents tell her she has to change schools, she is devasted. She can't imagine leaving her new friends at Chestnut Hill or her favourite pony, Colorado.
 
Lani will do whatever it takes to stay - even if it means giving up riding... But has she left it too late?