If you aren't physically dependent on opiates, and are using them recreationally, I see little point in re-dosing as it does kind of lead to a waste of opiates. A few opioids I might call an exception, but generally for regular opiates re-dosing just doesn't seem to be the best thing in terms of recreation. You can re-dose though if your tolerance allows you to, that is you won't get sick from taking too much, and don't exceed 2 grams of APAP in a single dosing period or 3 grams in a day.