You can't update a drawing from a template, but you can update it'sborder and metadata from a sheet format and it's drafting settings from a standards file.
There isn't a tool built into SolidWorks to do this to multiple drawings. You might want to check in the API forum and see if anyone has written a macro for doing this that they'd be willing to share with you.
There are also user-created utility macros on 3DContent Central too. You might find something useable there.
You can achieve this using API SetupSheet5 Method (IDrawingDoc), take a look at the following link for details,