It'd certainly be worth it if you plan on having the mortgage for awhile (I assume since you are retired you are planning on it) since you still have a ways to go before the mortgage is paid off.
Yes it is worth it, you will save $1,800 a year, which you can use to pay your property taxes and insurance. In 2 and half years, you recuperate the money you spent in the refinancing. Besides, I am assuming you need the savings right now.
