If you intend to create a MPP new file for each new "event", then
consider making a Template for the framework logic of the "event". BUT,
ensure you are are defining the project correctly, e.g. not as DATES but
as tasks with "fixed duration", or "fixed units", or "fixed work".
Or, if it's tasks copied from "above" down "below" inside of the same
file, again, if constructed correctly without dates but with "fixed
duration", or "fixed units", or "fixed work", you only have to fix the
date of the start task of the "event", or even better make the
predecessor task one of the tasks above.
I get the sense that you have built project plans where you input the
start and/or finish dates of the tasks ... and that's the wrong thing to
do with Project.