If you are able to get a lower rate that what you currently have, you can save tens of thousands of dollars over the life of your loan. Also, most lenders don't charge as many fees to refinance a mortgage and depending on how much equity you have in your home you may be able to roll the closing costs into your new loan, still have a lower balance than your original loan, a lower rate, and a lower payment.
Before you refinance a loan, make sure that you carefully analyze any fees that your lender is including on the loan. The Department of Housing and Urban Development can provide you with a list of standard fees. Use it to make sure that your lender isn't tacking on anything extravagant. And by all means, compare their fees with other lenders in the market.
Be Ready. After your loan is approved, you'll need to sign your loan documents and provide a check for any out-of-pocket closing costs. Make sure the funds are available in your account, and be ready to make room in your schedule to read and sign your loan documents as soon as possible.
If your new mortgage rate seems too good to be true then it probably is. Check for hidden fees in your mortgage that will make up that suspicious difference.