dspencer - Before you make a decision on replacing your existing battery I would check the date stamp on the battery to verify it's age.
Which ever route you decide to go, make sure your keep your original purchase receipt handy in the Trailer. When we owned boats I had to replace one battery a few times under warranty until I finally got a good one. I bought the original battery in a pinch against my better judgement. Also keep in mind that there are very few battery manufactures and they just slap different brand names on them. I've always had great results with Interstate Batteries.
Doug