Something I tend to do that helps me roleplay and stick with a character is saving and taking a break from one character when I finish something. For example, I start a new character, play until the end of the sewers, and save and quit. Then I load one of my other characters and play with them for a while. I eventually make it back to the character who's just left the sewers, and I go visit Jauffre. After conversing with him, I save and quit to p;ay on another character. It's as if the lives of the characters are TV show episodes, in a way. Dungeon-diving? Clear it and switch characters. I've got a bout 6 right now. Lol. May not work for you, but it seems to for me. :]
That's pretty much what I do, but not quite that rigidly. At the moment, I've got 20-some active characters. Some I haven't played in months, but most of them have been out at least for a bit at some time in the past month or two. I play my characters as separate individuals-- they're the ones who are living in Cyrodiil and I'm just pushing buttons and following along as they go do whatever they do. As long as I'm interested in one and have a pretty clear idea of what s/he wants to do next, I keep playing it. When I reach a point at which I'm not sure what the character would want to do next or I just get the urge to play another of them, I park the current one and switch. They're spread out all the way from level 1 to, IIRC, level 34-- all different races and genders and classes and abilities and personalities, so pretty much whatever I'm in the mood to play, I've already got going somewhere. And if not, I create another one.
ALTHOUGH-- Zak-- I know that doesn't help you, because you've got a completely different set of obsessions than I do.
All I can tell you-- I think it's great that you've said you're not going to do another ZS character. Stick with that, but don't stop there. Don't make him an Atronach, don't rush immediately to get the Spelldrinker Amulet, don't spam alchemy.... don't do all the things you keep doing over and over, because that's why you get bored. You already know how it works, and you end up god-like by level 20 and it's just not worth it to do it all the same, all over again. So you lose interest and decide to start a new character, and you hem and you haw and you try on this idea and that idea..... and you end up with a young, male Atronach who rushes to get Spelldrinker and spams alchemy.
I sincerely think, and I've told you before, that you need to get rid of all of your preconceptions about what sort of character you want to play and do something ENTIRELY different. The easiest thing to do is play a female character-- that, all by itself, makes it impossible for you to just sleepwalk through the game, doing all the same old things that YOU would do. You're not her and you can't be her-- she's her, and that's just the way it is. So you have no choice but to get to know who she is and what she's interested in and play the game the way that SHE wants to play it-- not the way that you do.
I'm willing to bet that if you play another young, male Atronach who spams alchemy, you're going to be back here in a couple of weeks (if that), bored and looking for ideas yet again.
Just my $0.02.........