Chickens aren't machines, she will lay as much as she can as long as she receives proper care and nutrition. You can't do anything else to make her lay more. This time of year laying can be sporadic because of the decreasing daylight. Production is at it's highest in the spring. A hen can't produce eggs unless she's being fed good food. You haven't mentioned what they are fed or how they are housed, which are things that can affect laying.