The modded sysap.exe (which gave you the "restart" option on power button menu on my previous custom firmwares), is a little bit more complicated to apply on the latest firmwares. Which is the reason why it is not integrated by me anymore.
I think this application is a nice replacement, if you are only looking for that feature.
Apply it as a shortcut on your home screen and you can restart your device with one button ;)
This application is free and was originally shared by syarmwawa (not sure if he also is the developer).
You can find the original post, where I downloaded it from here:
I created a new icon for this application, to match the look of the Anna/Belle icons of the latest Symbian versions.
Btw. this application is working on all Symbian versions. The installer is unsigned, your phone needs to be hacked.