I am looking to refinance my Harp Loan with SBA, but I already have an existing disaster loan with SBA. Tyring to get the best term and lowest rate possible. Is this possible?

If you are referring to the Small Business Administration (SBA), then they would not be able to help with a HARP Loan as SBA only provides a guaranty to a lender and do not have anything to do with residential loans. If you do have a loan that is Harp Eligible, you can work with most lenders to refinance your loan. Your 2nd Loan (disaster loan) should be a 2nd Lien and can be Resubordinated to allow your 1st Mortgage to be refinanced.