Some great training drills for goalkeepers on the Armagh GAA website here
. They are also on youtube
What sort of tee are you using?? I'm no expert on kicking from the ground cos we can kick out from the hand, but when I was working with a younger keeper, I found that he had a habit of getting over the ball when kicking. He was only getting it out around 20/30 yards (under 14 keeper). Anyway, we worked on it and he got better, kept onto him to lean back when kicking the ball
Make a kicking routine, step back a certain number of steps and make sure that you are leaning back to get height on the kick. Kick through the ball - some of those puntees are too high and can hurt your foot. Some guys prefer using a couple of space markers as their tee. Examine your run up - the fella I worked with used do a few dance step during his run up, which is okay for guys that are used to being in goals and have worked on strengthening their legs, but for someone coming into goals, I'd advise to have a straight run up to kick the ball. It is a lot about practise - I know from kicking the ball out myself that it does involve practise and getting a good routine going.
If you go over to the fitness forum, they might be able to give you some advice about doing leg strengthening exercises. At the moment, with your kickouts only going that far, you need to work on a tactic with your midfielders, such as the two of the them starting in the middle and running out to the wing to collect the ball, while keping your half backs quite near the goal, so as not to crowd the space