You want to plot total energy, right?
First you need to integrate the energy over the entire domain.
In Paraview, go to Filters -> Alphabetical -> Integrate Variables
Spreadsheet with the values should pop up.
Next if you want to plot this over time, click on the render view and select only IntegrateVariables to be shown. It will be simply one point. Using the tools right above the view Select this one point and then use Plot Selection of Time filter (Filters -> Alphabetical -> Plot Selection Over Time).
That's it, graphs should be generated.
Cheers