[THEjDonk]

Here's something you might want to think about when deciding if you're going to three-bet here:

1) What hand range do you put him on after his predraw-play?

After the discard, it seems likely that your opponent started with trips, two pair or a draw.

2) Why does he raise after the draw?

If he had a draw, he's either bluffing or he got there. You're probably not gaining anything by three-betting (the exception is if he cap-bluffs and you call, but that play is probably very unlikely).

If he had two pair predraw, he would probably not raise unless he makes a full house. I don't think he's raising without a good reason, because he would probably cap predraw if he's a "liberal raiser". Maybe he might raise with aces-up or something if he thinks you didn't falsecard to trips, but I don't think many opponents play like that at 1/2 (it might be common at play money and that kind of stakes).

Your opponent was obviously not comfortable enough to cap predraw. Maybe he thought that you might be three-betting with a pat hand. If he had small trips, I still think that he's not likely to raise postdraw. He probably suspects that you might falsecard. It seems like he's giving you credit for a strong hand (based on pre-draw play), so I don't think he expects you to have two pair (especially not two small pairs when you bet after the draw). So I don't expect him to reraise with small trips, but he'll most likely reraise if those small trips turn into a FH.

He might reraise with big and maybe medium-sized trips since he realized that you didn't have a pat hand. This is the only likely scenario where it's probably profitable to three-bet. Maybe these kinds of hands are more probable than made hands, but there are some other factors to consider. Maybe your opponent folds to a three-bet (a good opponent might be able to fold some trip hands there).

3)What will you do if the pot gets capped?

I'm guessing that you're going to make a crying call. Unless you know that your opponent is likely a maniac or constantly overplaying, you can probably not call that last bet comfortably. If there's a decent chance that your opponent is overplaying too much you can't really fold comfortably either. Getting yourself in a situation where you have to make a crying call (or a debatable fold) is not something you should do unless the reward for risking to get into that situation is significant enough.