I sort of develop my character's personality as the game progresses, shes been both cold hearted evil, and a knight in shining armor. Her development pretty much mirrors what I feel like playing at the time, and right now I just left all my items/gold at home and started a fresh life as a hunter.
lol me too... i normally plan my character but i found that adding some character progression throughout is fun too... the character i'm currently playing started off a a remorseless assassin too and i'm thinking of making her pay for her crimes by trying to do some good but then i wouldn't be able to let her become a vampire in dawnguard...

To the OP: I find that playing a jack-of-all-trades character seems to make you want to stick with him/her because... You have access to more skills? If playing character archetypes isn't for you, try making one that specialises in more skills?
Also, if you're on PC (console gamers apparently will be able to do it too in Dawnguard), try changing appearance (nothing too significant... eg. warpaint, hair etc) every now and then...

Hope that helps!