Can one improve his chess without playing online? I have been playing chess for almost an year and I'm addicted to playing chess on Lichess.
My stats there are:
2100 classical
2000 rapid
1800 blitz

I feel that playing chess online ruins my life and that my life would be much better without it at the moment.


I'm studying at the University and my grades dropped.
I'm not devoted enough in my work place.  
I'm barely going out with my friends 
I do less sports
I dropped some of my other fun hobbies
I sleep very late 
I barely go on dates


All of these are results of my online chess addiction.
However, after all that said, it makes me sad to think that I will give up chess completely. I still want to keep my playing skills and improve.

Can a chess player keep himself in shape only by studying chess (which is not as addictive as playing online) and playing long time control OTB tournaments once in a while? Or should I quit chess completely? 

Please help me by finding some things that I could do to stay good at chess while not playing online.

Edit:

I'm mainly addicted to blitz, the problem is that I lack self control to retain myself from playing it. I tried a few times to stop playing blitz only but failed to accomplish and went back to my bad habits. I wish there was an option to open an account that would be allowed to play long time control games only to help people like me. Once I play blitz I usually just crave to reach a specific rating and I play like am possessed. 

I started playing in a local chess club a few months ago. I already got to play 3 long time control tournaments, quite sucessfully and I want to keep my level there. I fear that without this abusive online playing my abilities OTB will be damaged
I'd like to start with this comment of yours:

&quot;I fear that without this abusive online playing my abilities OTB will be damaged.&quot;

I know where you are coming from, because I've been there, too. I used to be ridiculously addicted to chess - and I wasn't even very good lol. Now it's a hobby, which is much more healthy.
I also know that fear you speak of - I, and people like myself (which presumably includes you) strive for depth, rather than breadth in life. Being very good at one thing seems so much more important than being kind of good at a lot of things; trouble is, I picked the wrong thing.
Personally, I had to completely stop playing chess for a while. When I came back to it (in a more recreational fashion), I was indeed worse at chess, and though I have improved, I'm still not completely back to where I was (although I strongly suspect I'll get there).
It was completely worth it.
I had free-time. I had sleep. I had better grades. By golly, I even had more friends - not fair-weather friends, but honest-to-goodness friends that cared about me and my life.
I say all of this to encourage you that even if your playing ability drops off, please don't worry about it. Chess is not your life. Your life is your life. Go out and live it! Study with all of your strength, go on dates, hang out with your friends, work your rear end off and become the absolutely amazing, incredible person that you are - one that's always up for a relaxing game of chess with a friend, of course.

Now for the practical suggestions:

Here are some suggestions for maintaining playing strength while limiting online chess:

Study master games. Seriously, doing this will get you way more chess knowledge than playing oodles of blitz games.

Read some chess books, playing out the games on the board if you wish. These books are almost always entertaining as well as being extremely helpful.

Play casually OTB with some friends, analyzing various lines at a relaxed pace - chat with a friend (or maybe even a date) over a nice, no-pressure, slow game (although if it's a date, make sure that she likes chess first XD).

Visit you local chess club, and play some games there when you're in a good spot with your schoolwork and workplace work.


TL;DR: it really is possible to enjoy chess and have a life.