Now that the corn season is underway, someone in the house is steaming corn almost on a daily basis. Is it safe to leave the pot on the stove(covered) with the water in it and reuse it 2 or 3 times before discarding and starting fresh? Sugar has been added to the water.
No, it is not safe; what you would have left in the pot would have the <2-4 hours worth of safety at room temperature as anything else. What you would have in the pot after steaming corn is sweetened corn broth; it will mold and it will grow bacteria. You would probably be fine 9999 times out of 10,000, but considering the expense of starting fresh every time, there is no good way to justify the risk of saving the water.