I'm on PC and in my play through i have already beaten mother ship zeta, and i herd that it gets a lot tougher at higher levels so i was wondering if there's a way to reset the quest and let me play through again with the same character

Nope, the only thing you can do is create a new character.

I heard that you could uninstall MZ and reinstall it, and that allowed you to play it again. i've never personally tried it so i don't know if it works

I's not that it's tougher on higher levels....it's just a hell of alot more tedious.

If you finished it....just forget it

the only way to do that is by deleting MZ and reinstallling it, but then you loose all of the loot you get from it

there's a mod on Fo3 nexus that lets you redo MZ.