You can reuse cooking oil for a maximum number of three times. However, you should avoid reheating cooking oil, as it can release toxins that can adversely affect your health. You’ve probably considered storing the wasted oil and reusing it for another dinner at least once. It’s a simple question with a complicated solution.
Keep a fine mesh strainer by your pot as you fry foods and use it to periodically clean up your oil by picking up and discarding any bits of batter or breading that may have fallen off your food. Stick with Battered foods or Bare Vegetables. Battered foods will impart far fewer impurities to the oil than breaded or flour-dredged foods.
Less hydrophobic molecules in your oil means that it can come into closer contact with foods, allowing them to fry just a bit more efficiently. This is where the wisdom of those tempura chefs comes in— adding a bit of degraded, old fry oil to the new batch will improve it.
You can submerge a piece of food in a pot of hot oil and not much oil will get absorbed—at least, not until enough moisture has been driven out of the food. The more oil breaks down, the less hydrophobic it becomes. At first, this can actually be an advantage.