what is your previous rate? Bear in mind

The interest you paid for your loan is only determined by your principal and interest rate,and is the part of the payment you want to lower down, it doesn't matter how long have you paid the loan. if it's no point no cost refi, I think it's worthy of doing that. As you may want to sell it in 3-5year, then you can consider 5ARM which will lower your interest payment further.