There are so many variables to this question. Some include:
1) Age of Competition-
14U, your main focus should be throwing strikes, and changing speeds. You're more than likely on a pitch count. Dont waste pitches.
2) Base runners-
When you have runners, especially in scoring position, you dont want to throw a risky waste pitch that the catcher may have difficulty receiving.
Bouncing a Breaking ball, or reaching back for that "little extra" on the fast ball, to throw it past your catcher to have the runners advance, or God forbid score, is far worse than having the batter put the ball in play. Plus the batter still has another strike, and is now more confident you are going to throw a pitch he can hit, due to the previous outcome of the "waste pitch".
3) Batters Composure-
What has the batter told you in these 2 pitches? If the batter watches a pitch go by, the umpire calls it a strike, and the batter proceeds to throw a fit. THROW THE SAME PITCH AGAIN!! He just told you he cant see that pitch. Make him prove to you he can handle that pitch before offering him something else (If your catcher calls for the same pitch again, and you dont know why, the batter may have very well "quietly commented" on the pitch. Another reason to throw what the catcher calls).
4) "How" did the count get to 0-2-
Did he swing at a first pitch breaking ball? Is he pulling foul balls or swinging late?
If he swung at an opening breaking ball, and missed, throw another one for a strike. Dont bounce it or get cute with it.
If he has pulled 2 fast balls foul, pull the string. Dont be afraid to.
If he is swinging late on the fast ball, climb the ladder. (preferably inside half, but I believe the elevated pitch is more important). Now is not the time to go with anything off speed.
5) Your Ability, as a pitcher, to hit your spots-
If you are going to throw a waste pitch you need to make certain you have the control to put it in a spot that is going to take advantage of the batter trying to protect. Throwing a pitch 2 feet outside, or a foot in front of the plate does nothing but get the count closer to the favor of the batter.