ORIGINAL: wallhangr
I would spend the money on a new bow IF you are not satisfied with what you have. You can always improve your assessment of distances with practice.
I'm happy with what I have, but it's always fun to get shoot new bows - the same applies with guns too. And besides you can never have too many of either

I would argue however, that while practice will make you a much better shot, people are notoriously horrible estimators of distance - there are of course exceptions to this, but as whole runs true. And nothing can beat actual data when it comes to knowing distances.