you are talking about different things here, but what stars and saints have in common is that they are predetermined until a certain depth. for saints i believe its 15 steps and for stars its 10 until new stages are added. so there is no magical chant or voodoo to perform, no glitch or anything like that. if you got unlucky and the next 10 star stages are predetermined to fail, then there is nothing you can do about. just be patient and hope you will get more lucky when it really matters and it comes down to the purples.