In BO3, you can only use the restart level button in offline, local mode. With the following patch in your mod, you can add it to every mode, all the time.
Download the following file: DataSources and place it in the following directory
Finally open up your mods zone file and add the following line to override the stock one:
NOTE: The custom container must end in *.luac because it is a precompiled file!
This uses the mod override function to ensure that we load our tweaks first, you may be able to do this in a map via forcefully loading the file under a different name, on load, with the
LuiLoad function in csc.