I also posted this on the nexus.

http://thenexusforums.com/index.php?showtopic=182602

So I installed the KseAliLeveling mod, and it worked great.
http://www.tesnexus.com/downloads/file.php?id=3932

However, when I uninstalled it to switch to Oblivion XP, the level up menu
is just showing the level up message in a box completely devoid of attributes.

What should I do to get my options back?

If I didn't provide enough information, please tell me.

Thank you.

Did you do a clean save in-between?

Remove KseAliLeveling.esp, load oblivion, make a new save, quit oblivion
Add Oblivion XP, loading oblivion, load your clean save and it should work.

edit:
It may also be something specific to Oblivion XP but I never used it so...

I hope you installed all of OblivionXP, which has it's own level-up xml files.

Also, make sure you are running a current version of OBSE (version 18b6, preferably)