Most places that sell batteries will test yours for free hoping to sell you a new one. Even Walmart and Sears.
If you have removable fill ports, you might just need to fill the battery with more water to extend its life.
You may want to go to the place you bought your last battery. Some have free or pro-rated warranties depending on how old the battery is. They usually have markers on the battery so you don't need your receipt. I think most expensive batteries are free replacement up to 2 years and pro-rated up to 6 or 7.