I'm in a similar position - about the same hours. I did a 8 hours of night training last Oct/Nov and I've done the Instrument course. Both of those sharpened my flying and made me less tense & more accurate. The other thing I do is to fly with an instructor for an hour whenever possible - be put through the mill and challenged. Much better than the annual check.
I am aiming to get JAR CPL - when they can be bothered to have heli-specific ground exams. Which, I understand is not too far away. Could someone post some guidlines here about the current state of play on CPL (H) - the CAA site doesn't help.
Lastly, when the vis is bad and the wind close to limits - go do some airfield hovering with an instructor. Cleanses the senses!