If you would like your competition to have the same structure it did in a previous year, you can import a previous competition as opposed to rebuilding it.
To start the process, create a competition. Prior to building your rounds, click the settings cog in the competition toolbar, and select "Import previous competition".
If you cannot see the settings cog, make sure you are in edit mode, not results mode.
After clicking "Import previous competition" you will be prompted to select the competition you are importing.
If you do not see any options in the source competition drop down, it means there are no previous competitions, or if there are, they are not compatible with your existing intake.
Once you have selected the competition, click "Import". Your competition structure will now mimic a previous competition's.
Note: Round dates and titles are also imported from the selected competition.
Updating Competition Structure
Unless the competition you imported has the exact same schools and dates as your new competition, some manual updating will likely be required.
Missing Schools (Knockout)
The import function will allocate schools to matches based on the match structure of the imported competition. If a school did not register for this years competition, but they were in the previous competition, the competition builder will display an "NA".
To resolve this, switch to edit mode and delete any "NA" entities. You do this via the bin icon.
A deleted entity will then allow you to drag schools into the match in their place. Any schools that have not yet been assigned a match can be found under "Match Candidates".
Missing Schools (Pool)
If the competition you're importing utilises pool rounds, you may need to edit the pool settings to remove/add any missing schools.
To clean up a pool round, switch to edit mode and click the blue edit icon next to the pool you wish to review.
This will bring up the pool editing modal, and similar to knockout rounds, any missing schools will be marked with an "NA". The placeholder title will still exist from the existing competition. 
Click "Remove" next to any entities marked as "NA" to delete them from the pool. If you need to add a new school to this pool, you can do so as per normal.
You will also need to recreate the individual pool matches with the new school data. This is done in the same edit pool modal, under "Advanced Options". Click "Show" then click "Reset pool rounds & auto map matches into rounds".
Editing Round Dates/Titles
Importing a competition structure also imports the round titles and dates, which often need to be updated. To do this, make sure you are in edit mode, and click the blue edit icon next to the round title.
From here you can update the round information accordingly. Once you are happy with your changes click "Edit".
Though importing a previous competition does a lot of the heavy lifting for you, it can create extra work if the competition's entries are vastly different. You can read more about editing/creating competitions here.