The premise goes something along these lines:

Akane and Ranma have some really major fight one night.  Akane would then
chase Ranma out of the house for the few days and ends up missing.
 Eventually Ukyou finds Ranma and brings him, and he's caught some kind of
really bad fever.  Ranma ends up dying and the story concentrates on Akane's
struggle with guilt for never telling Ranma how she felt and how lives the
rest of her life emotionally crippled.  She wants desperately to commit
suicide, but after her first attempt, she learns that Kasumi is honorbound to
commit suicide if anything should ever happen to Akane since Kasumi functions
like Akane's second mother.  Akane then lives out the next eighty years in
misery, her only heartfelt companion being the orphaned daughter of Tofu and
Kasumi.  When Akane's stepdaughter falls desperately ill and Akane needs
money to pay for the child's treatment, Nabiki tells Akane that her life
story is prime material for a best-selling novel.  Akane ends up becoming a
renown Japanese author, but is hardly anymore content with her life (ie
success isn't happiness).  On the day she dies, however, Akane wakes up in
her room and finds herself sixteen years old again some days before her last
fight with Ranma.  She slowly suspects that the life she lived for the last
eighty years was a dream, but she later finds the book she wrote on her desk.
 Akane slowly realizes the magnitude of her blessing, that it is an uncanny
second chance to for her to relive life the way she believes it should be for
her.  Her memories and the lessons of her past life remain intact, and Akane
expresses new appreciation for her unsuspecting fiance and their destiny.  

Let me know what you think.  I've been turning this around in my head for
quite some time, but I'm not eager to write up something this big if the
masses out there think it's not a concept worth the effort.  Thanks

Sakkahito