It depends on the terms of the original loan, the terms of the new loan, and how long you plan on staying in the property. Every refinance has a "break even" point, or how many months of savings it will take before you save more than the refi costs. For example, if you are going to save $100/mo and the refinance costs $3600, it will take you 36 months to break even. If you plan on staying in the house longer than that, it makes sense to do it.
You can refinance with your original lender or a new lender.
