Metaphysics : Why do things that repeat themselves include pleasure?

not sure what you mean by "meditated by pleasure", unless that was a typo.

but it's not too hard a concept to understand: pleasure good, pain bad. it's something our "reptilian brain" learns early on. the "human brain" learns to understand what CAUSES these things, in the big picture, and how to make them happen long term, which is what most working people strive towards.

also, not sure what you mean by sweets and chocolate "repeating themselves". it is actually PEOPLE who choose to continue or not to continue eating them, based on positive or negative experiences. if somebody has a trauma with something that is generally considered pleasurable, they are unlikely to have the same sense of wanting to continue it.

if somebody sees that they are getting fat by eating too much sweets (or eating too much in general), then they will likely try to eat LESS, thus bringing them the pleasure of LOSING weight.

Most will agree that pleasure is a physical phenomenon. A more logical approach is needed.

Generally speaking, the things that give us pleasure are the things that perpetuate the species: eating, having sex, seeing our loved ones healthy and happy, etc.

In these more complex modern times, and given our complex human nature, the general rule doesn't always apply. Our tendency to seek pleasure often results in disaster, but it is still consistent with evolutionary principles; evolution is, so to speak, a mad scientist that conducts all sorts of strange nonsensical genetic experiments. Once in a while it hits upon a advantageous result. Behavioral diversity is comparable to genetic diversity. A variety of behaviors is advantageous. For example, in a given situation, those that stand their ground, and fight, might all die, but in doing so, they might enable at least some of, those that run for their lives to live. If all had fought, or all had run, perhaps there would be no survivors. I'm not saying that having sex with an apple pie necessarily helps the species survive; I'm just saying that experimental and/or aimless behavior is in our nature, and plays a role. 

That would seem to be a far better question to ask in the psychology, biology and / or anthropology forum.  I've studied metaphysics for a very long time and have yet to stumble into any philosopher or philosophical treatise that addresses this head on, while addiction, pleasure and repeated behavior falls squarely into the realm of behavioral psychology.

I would say it's more "instinct" than "metaphysics," but in general beings are "programmed" to associate things necessary for survival and procreation....which are the two basic functions of all species...with sensual pleasure.

Whether you want to call that programming "divine design" or the happy accident of millions of years worth of natural selection, the simple fact is that pleasure more often than not points us in the direction of things that contribute to our survival.

Seeking warmth and comfort feels better than staying outside and sleeping on a damp rock...it is also better for survival.  Sweets tend to give us life-sustaining energy while bitterness is associated with poison.  Good smells are associated with a range of life-affirming things from good foods to good hygiene...while foul and unpleasant odors tell us to stay away from things bad for us.

And the simple reason why sex feels so good is because our instinctual "wiring" wants us as a species to reproduce as much as possible.

We become addicted to pleasure-inducing things because the converse of pleasure seeking is pain avoidance.  Pain means damage which means danger to the species, so we are equally hard wired to avoid pain. That "wiring" can sometimes be defective and lacking in the natural  "regulators" that prevent excess.  

If you break down most addictions, you'll find that most involve pain/fear avoidance.  Drug addicts are continually medicating themselves.  Codependent personalities and sex addicts act to mediate the pain of loneliness and alienation. Thrill seekers and "adrenaline junkies" are driven by the need to constantly overcome fear, and so on.