Generally, you need to be aware of what the interest rate you're paying on your mortage is. When interest rates start to go down, you have to be ready to jump on it and take advantage of a lower rate. It generally costs a couple of thousand dollars to refinance, though, so you need to think about several factors before deciding whether or not to do it.

First, how much are you paying now? You need to know both your monthly savings and the amount of time you expect to be there. Only refinance if you're sure that you will be staying in that house for awhile - moving and selling your house would wipe out all the benefit of refinancing. You also need to think about whether interest rates will go lower in the future. You don't want to jump on a refinancing and then suddenly find out a few months later that interest rates have dropped a point. Even a small change in interest rates can produce a large gain over the life of your loan, so you want to make sure you're refinancing at the low point. Talk to your bank loan officer - they'll generally tell you whether they think it's a good idea and what direction they think interest rates will be going. Ask them to show you specific calculations, and then check them yourself. They'll easily be willing to do this, after all, they need you to be able to make a sale. Mortgages are their business, but yours is making sure you get a good deal.