Should I keep my 2012 Honda Civic? Or upgrade to Si?

The 2012 Honda Civic 4 door lx is my very first car. I've had it for two years, going on three. Now, this car is by no means powerful and only sports a measly 1.4L engine. But there's just so much memory in this car. I drove it to see my favorite rapper, Riding through the city with friends. When I look at the car I don't see the civic, but the memories that are in it. Should I upgrade to the Si? Or just keep my car and add after market parts. I will definitely be sad to see this car go, if it comes down to it.

One of the things in life is to remember your "First" if not cherish them while you still can. If I were in your shoes, even I have no idea about your situation. I would keep the car if the only thing you want is a little bit more power in the Si. Sometimes I've wished to have my "first car" back (Sold it when my first child was born: A Datsun 240Z).

http://www.thecarconnection.com/overview/honda_civic-sdn_2012

I would keep It, but if aftermarket parts means spoilers, popcan exhausts, and slam and camber it. Than buy the si which is also slow.

In cases like this, all the specs in the world aren't going to make a difference because the power of human emotion is way stronger than an improved engine.
What I do recommend is this, go to a dealership and take a test drive. Pay attention to how the car makes you feel. When you take corners, do you feel connected to the car or is there a level of separation? Is the engine eager to deliver power when you ask for it? What about the interior, is it comfortable, do you see yourself having fun in the car? If all those little details make you feel happy enough to the point that you could sacrifice the already made memories in hopes that the new car will give you even more fun memories, then go ahead and get it. If you feel that you aren't really satisfied with the car and that it's not worth trading those memories for the new car then don't get it but at least you'll know you aren't missing out.
if you don't feel that it is worth it then take a look at buying aftermarket parts for it. Hondas have a huge market for this so you shouldn't have any issues squeezing a couple more hp out of the engine.