You can create a new version of the policy by navigating to Policies>Policies in Progress>Options>View Policy>Create New.
This will then archive off this current version of the Policy by taking it out of circulation; a new version will then be created allowing you to make any required changes.
If you wish to create a copy of a policy without archiving the current policy, you will need to ensure the policy is a Template. You can now create new versions of this as many times as you wish without any archiving.