If my i-90 application is denied, will I be refunded?

Few refund exceptions apply.

No. USCIS does not refund a fee or application regardless of the decision on the application. There are only a few exceptions to this rule, such as when USCIS made an error which resulted in the application being filed inappropriately or when an incorrect fee was collected. CITATION* http://www.uscis.gov/iframe/ilink/docView/AFM/HTML/AFM/0-0-0-1/0-0-0-1067/0-0-0-1740.html