Richard
A 12.5 is probably a good choice for that scope. As you have a 25mm that will give you low power view at 26x and the 12.5 gives you 52x.
Personally if you have only had the scope a short while I would suggest holding of spending much on eyepieces or new scopes but spend as much time as possible getting to know your scope.
I assume the scope is one of these?
http://www.celestron.com/astronomy/c...ar-130slt.html
How have you found the Go To capability of these? and how are the views that you have seen so far?
Malcolm