There are products that contains hormones to promote the formation of keikeis.
You can also grow the plant in a dark place and it might send a keikei. But you will not get any blooms if you grow in a dark place. I haven't had a keikei before in my life, but my aunt did and she did not grow her plant close enough to a window...more like far away from the window and behind a large pot (this was her first orchid). No blooms but a new plant I believe the dark place method is in literature somewhere, but I read it a while ago.
I recomend buying the hormones, it's just easier.