I played hockey for 9 years. Lunges with moderately heavy dumbbells will help. Try to do them as fast as you can while still maintaining a controlled movement. Squat jumpers are good for building 'explosiveness' (remember those from like jr. high PE?), squat and bring your arms to your sides, then quickly jump up as high as you can and swing your arms up - then repeat. Also, sprints on ice... I know sometimes good ice time can be at a premium though