How do you refinance with the same company you have the loan through?

I have a loan through Wachovia for my truck. After a year 1/2 of having the truck the payments have become a strain, how or when could I refinance the truck using the same company? (I really enjoy Wachovia, they are great and have helped us before. I would prefer to refinance through them) http://bit.ly/rj9rho