Glass Mask 3 times. Saw it for the first time in 2006 or 2007, and 2 times this year. i deliberately avoid watching it again because i become too emotionally involved and nostalgic each time. I could watch it thousand times and never get bored. It has such a classic atmosphere. Video quality could be better BUT theres a huge gap in tech between 1997 and 2016.

Secret 3 times ( cry like a baby each one of those)

Liar Game - 4 times and that is only the Korean version,I have watched the japanese one as well.
I have re-watched certain episodes of ( Empress Ki and Healer , It's Okay That is Love) several times but not as a whole anytime as I go to other new dramas instead of rewatching for most of the time.
I don't usually re-watch dramas and movies but I've seen Orange Days (Jdrama) and A Moment to Remember (Kmovie) twice each. I can't recall watching anything else twice. 

Which reminds me...we need a column for this in our drama lists. Who's with me? ~
The only one that I have seen + than twice was LIFE (Jdrama) And I am planing to re-watch The lover (Kdrama) wich is a non-stop laugh I really recommend it.

I agree with you too Fortuna!
The Master's Sun! hell yeah lol
Queen In Hyun's man, You who came from the stars, Descendants of the sun, Creating Destiny, Arang & the magistrate, City Hunter, Faith, Secret Garden, You're beautiful... well yeah I have alot :,D I just like to go back to my favorite dramas once in awhile :D 
fated to love you both versions
1 litre of tears
love that make u cry
koizora
Scarlet Heart Ryeo
Faith
Cruel Romance
Prince of Ling Lan
Tree Of Heaven
Beautiful Days
Mars
 
I like rewatching my favorite dramas.. :)

Dramas I've rewatched more than 5 times were:
Secret Garden
Queen Seon Deok
YWCFTS
Healer 
Oh My Ghost
Dream High
Moon that Embraces the Sun

Dramas I've rewatched 2-3 times were:
Signal
Cruel City
White Christmas
It's Okay, It's Love

Cruel City
Its okay that's love
Winter Sonata
Full House
Fated to love you Korean version
Chuno

I've never re watched dramas besides Descendants of The Sun (My first drama)
Only White Christmas (masterpiece )
I am a re-watch kind of person so most of drama/movies I've watch more than once (whole episodes) but the most that I watched is

Ugly alert- Korean drama consists of 133 episode- watched it more than 15 times
 I dont know the exact reason why but its storyline attracts me with Im Ju Hwan as the lead. He potrays his characters really well.
Goblin, Goblin oh & did I mention GOBLIN!!!
Noble, My Love
Gokusen
I Hear Your Voice
Strawberry Night
Biscuit Teacher and Star Candy
City Hall 
Coffee Prince
The Greatest Love
Scent of a Woman
Kimi Wa Petto
I do, I do
Devil Beside You