Yup, cep2_add_sb_v1.hak is your problem. When a blueprint is stored in a hak file, any changes you make vanish when the toolset is closed. Until that point, your edited blueprint is actually sitting in your NWN/modules/temp0 folder. Look for the recently modified .uti files. You can copy them out of the temp0 folder before saving/closing.
After saving a copy of your modified blueprint, remove that hak (and possibly cep2_build.hak) from the module's custom content list. You'll lose any other blueprints that were stored in that hak. Save, close the toolset, and reopen it. Reopen your module, copy the modified blueprint file into the newly-created NWN/modules/temp0 folder, go into the toolset, right-click on the item palette, and pick "refresh palette". Your modified item should now appear properly.
Or (assuming you're making a multiplayer server and not a single-player module) you can keep the blueprints hak as it was, put your modified blueprint file into cep2_custom.hak and add/move that custom hak to/near the top of your hak list for the module. Doesn't work with a single-player module though, since you don't want to give players an alternate form of the cep2_custom.hak as it could mess with any other CEP module/server they play on.
For CEP 2.60, I'm going to be moving cep2_add_sb_v1.hak to "legacy" status...keeping it in the download to stay compatible with older modules that might use it, but moving any blueprints within it to one or more .erf files. Just because of this "pain in the posterior" process that having blueprints (and scripts) in a hak causes a builder to go through to change anything.
The starter module I make for 2.60 will not include the hak-stored blueprints or scripts.