There are several methods for upgrading an individual installation to a new SolidWorks release.

When installing a new major release, you can upgrade a previously installed major release or install the new release in parallel. If you are installing a Service Pack release for a previously installed major release, that release is updated automatically.

• Checking for Updates Manually
  You can check for updates for a currently installed SolidWorks release using one of these methods.
• Upgrading Workgroup PDM Clients
  Workgroup PDM clients detect when the Vault has been updated. You do not need to download a service pack to update clients.
• Upgrade Caveats
  Products that can have multiple installations with different major versions do not always support major upgrades, or the ability to upgrade between major versions as a single operation.