Emergency Couple (2014) Both dramas are about divorced couples which meet again after some years
Paradise Farm (2011)
Meeting again after they choose to separate. Faith makes them reconsider their feelings.
Get Karl! Oh Soo Jung (2007) it's about getting revenge from your Ex, but here, it's the male lead getting back at his runaway bride
The Master's Sun (2013)
The male lead has the same childish cuteness. So If you are looking for a drama with a similar male lead, this one is dev something for you!
Office Girls (2011)
Qin Zi Qi is very similar to Gook Seung Hyeon, both are heirs that have to go incognito into their own firm and the main female teaches them how life should be lived at work.
Rich Man, Poor Woman (2012)
Both dramas' male leads are computer genius and CEO/founders of an IT firm.
Temptation of Wife (2008)
Cunning Single Lady is a romcom and funny while Temptation of Wife belongs to the family tragedy genre? Not really similar but both seek revenge on their husbands and funny fact the later one was mentioned/parodied in CSL-
I Do (2014)
Split couple developing feelings again and resolving all the misunderstandings, filling up each others' shortcomings etc
Lie to Me (2011)
Both Male Leads act a lot alike. Also they both go back and forth between love and hate relationship.