That's a hard one if you can't live fire often.
Try strength exercises:
using a 5 lbs weight and hold out as if you had the gun. 3xs, 1 min each, 30 sec recovery. (Increase as neccesary)
Regardles if you use a tight or < firm grip on the pistol, try strengthening your grip by using a grip strengthener, exercise both hands.
You really do need to spend quality time on the range. Try to really disect your lower and upper shooting platform. Sometimes, the technique may not feel comfortable until you are more familiar with it.