Are all of your animals veiled? You didn't specify. Also, just out of my own curiosity, you say 4 of them have laid, so, do you mean you have eggs incubating from 4 different females at the same time??
As far as "making" them receptive, I'm no expert, but I don't think there is a way to do that. They are either receptive, or they are not. If they are not, all you can do is re-introduce her to the male a month later, and continue in monthly intervals until she shows her receptive colors.
I wouldn't continuously show her to the male daily, in hopes that she will be receptive, because she more than likely wont be, and you would be causing her unnecessary stress.