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.
If you are refinancing from one ARM to another, check the initial rate and the fully-indexed rate. Also ask about the rate adjustments you might face over the term of the loan.
Changing the term of your mortgage can help in several ways. First, if you were to refinance your current mortgage from 30 years to 15 years, you will accelerate the rate at which you pay towards principle each month meaning your house will be paid off quicker. Also, you will save an unbelievable amount of money in terms of interest because you would likely be taking 10 to 15 years off the life of your loan. Second, you can also refinance a 15 year mortgage to a 30 year mortgage. It seems like it might not make sense to do this, but if you have an immediate need to free up monthly cash-flow and you don't want to take out a home equity loan, this can work out to your benefit. When you take a 15 year loan and refinance it to 30 years you will have the same balance only the payments can be hundreds of dollars less than the 15 year loan. The only draw back to this is you will pay more in interest over the live of the loan.
Refinancing can be the right move to improve your financial situation, but be careful. Making the wrong move can put you much worse off. Smart and simple choices will go a long way toward keeping you financially secure.
If you want to make sure the interest rate your lender offers you is the rate you get when you close the loan, ask about a mortgage lock-in (also called a rate lock or rate commitment). Any lock-in promise should be in writing. Make sure your lender explains any costs or obligations before you sign.