You cannot do a "drop in" replacement of your chart of accounts; once it is selected and data entered, it is permanent.  However you can change the account numbers and account names of your current chart.

If you need to move some items into new accounts you can make journal entries to move from one account to another.  This allows you to retain your full history but have your accounting system move to a new plan.

It is a good idea to do this once (or twice, or more) on a test server.  Backup your production server, then restore it to a test server and try your changes until you are certain that it all balances correctly.

When you are certain that you understand exactly how to do the migration, you might consider waiting until your year-end to actually perform the update.