Build the house out of any material you can find that is free!
Would Dear Austin be a better book if it were just a light sequel? Write a letter to the author to let her know how you feel.
Do you like history? Dear Austin is a good example of Historical Fiction. Research another time or event in history (American or otherwise) and write letters to your brother, sister or friend just like Levi and Austin did.
Act out one of Levi's "scrapes" or a consequence (e.g. the plucking chickens).
Look up these words in the dictionary or thesaurus:
Misdeeds
Envisioning
Veering
Innocence
Resiliency
Risked
Marvel
Counter
Or...Find words in Dear Austin that you don't know, make a list and look them up.