You can choose a bundle to update from the Installed Bundles page, at Customization > SuiteBundler > Search & Install Bundles > List. The Action dropdown menu includes an Update option, that you can click to update a bundle.
SuiteBundles to Update Reminder
You may see a reminder in the Reminders portlet indicating that one or more installed bundles have an updated version available.
When the first bundle is installed in an account, this reminder is added for an account's administrators and for users with SuiteApp Marketplace permission. This reminder only displays when at least one installed bundle has an updated version available.
You can click this reminder to go to the Installed Bundles page, where you can click a link to update a bundle.
You can remove this reminder from the portlet by clicking Set Up, clearing the box next to SuiteBundles to Update, and clicking Save. Click the Reminders portlet Refresh icon to see the change.
Update Available Icon on Installed Bundles Page
The Installed Bundles page includes an alert icon in the Version column for any bundle that has a later version than the version currently installed in your account. You can click the Update option in the Action dropdown menu to go to the Preview Bundle Update page and update the bundle to the latest version. See Reviewing the Preview Bundle Update Page.