Try a pop-up drill...
1) get into your catcher's stance
2) Pretend to recieve a pitch
3) The just pop up remembering to pop up into your proper throwing technique
Simple...yess but this is something you can do on your own...you can also start on your knees and try to pop up...harder but can build some strength
1) put an empty bucket by second base (not on the back but just to the 2nd bseside of it
2) Stand at home and just throw at the bucket
3) As your accuracy improves, then do the drill in your catchers stance and pop up and throw