cooked pudding

Hi! I made cooked pudding from a box last night & used an old measuring cup. I was to put 3 cups in the pudding mix & I put in 3 measuring cups of 6 oz each in by mistake. I wondered why the pudding cooked so fast. As it thickened, it got really thick! Then I looked real close at the measuring cup & saw a 6 which I mistook for an 8. Is there anything I can do to make it more the consistency of pudding? Can I add more milk & cook it over since it’s been refrigerated or is there nothing I can do?:frowning: Thank you!