I'm looking for a drama life Life Plan A & B where the main person goes back in time to change their past or lives two alternate lives. I'm totally into the "what if" dramas right now and would LOVE it if someone could recommend me some. 

Post 2008 though please, my eyes can't handle low quality videos :)

This is a movie (not a drama), and it hasn't been released yet, but from the synopsis it sounds like it fits what you're looking for, in terms of story/plot: Will You Be There?
Some Japanese but most are pre 2008 (i'm still posting them because some are pretty good)
- Long Love letter (2002) (kind of)
- Proposal Daisakusen (2007)
- Ryuusei Wagon (2015)
- Tokio (2007, a favorite of mine but probably nowhere to be found, character travels through another person's past).
Toki wo Kakeru Shoujo (2016)
Akumu-chan - they don't do back to the past but can predict future events and try to change them
Mirae's Choice/Marry Him if You Dare is one.  I dropped it in the middle, and didn't hear good things about the ending, but it fits your description.
To Be Continued- A short web drama where the members of Astro find themselves back to before they debuted.

Project Makeover- A K movie where the main girl goes back in timeand meets her past self and tries to change the decisions she made.


Orange (japanese movie, the main lead receives a letter from the future and has to change her present to save her friend)
Proposal Daisakusen (the main lead has the chance to go back to the past to try to make the love of his life his)
Mirai Nikki (the charcters have a future diary)

all of these are japanese
Juunen Saki mo Kimi ni Koishite
Suteki na Sen Taxi (1 episode = 1 story with different characters in each episodes, very fun to watch)