I found myself getting sloppy about the way I perfom spells, try communication, do ritual.
Which makes things ineffective of course.
Don't know if this helps you, but I decided to do things a bit more formal again.
Can't even remember when it was the last time I casted a complete circle with all the frills.
As for exercises, focus-training and energy-flow, would be best I guess.
Try to run the energy through your body and then back, till it flows easily - then I'd try to charge stuff.
Hope you'll find a way to reconnect to your magic soon.
