If you choose to go with delete and recreate the Vault then below steps may help you,
Use the Export utility to export the items from the archive to PST
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a. In the VAC expand the <Site container>.
b. Right click on the <Archives> container and click <Export>.
c. In the Export Archive Wizard select <Export a single archive to a chosen mailbox> and click <Next>.
d. Select <List all available archives> and click <Next>.
e. From the list select the archive that is to be moved and click <Next>
f. Select <List all available mailboxes> and click <Next>
g. Select the user created in step 1 and click <Next>
h. Select <Export all items> and click <Next> twice.
i. Once the Export finished, click <Next> then <Finish>
Disable the user via the Vault Administration Console (VAC) by using the Disable Mailbox Wizard.
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a. Open the VAC and click on Tools then click on Disable Mailboxes.
b. In the Disable Mailbox Wizard select the Exchange server where the user account is located from the drop down list then click Next.
c. Select List all available mailboxes and click Next.
d. Select the mailbox from the list then click Next.
e. Click Finish.
Delete the old Archive in Enterprise Vault Administration Console (VAC)
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a. In the VAC, expand <Archives> then select <Exchange Mailbox>
b. Right click on the old archive on the right side and select <Delete>
c. Click <Yes> to confirm the deletion of the archive.
d. The Archive status will say "Marked for deletion
Launch the Enable Mailbox wizard to enable the mailbox that was disabled in Step 2.
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a. Open the VAC and click on Tools then click on Enable Mailboxes.
b. In the Enable Mailbox Wizard select the Exchange server where the user account is located from the drop down list then click Next.
c. Select List all available mailboxes and click Next.
d. Select Show Disabled mailboxes only and choose the mailbox from the list.
e. Click on Deselect Archive, then click Next.
f. Click on Change then click on Change beside the Vault Store and select the new vault store and click Next.
g. Choose the appropriate settings on the remaining dialog boxes and complete the wizard by clicking Finish.
Run the PST Import Wizard to migrate the exported data into the new archive on the new Vault Store.
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a. In the VAC expand the Site container.
b. Right click on the Archives container and click on Import.
c. In the Import Archive Wizard select the destination Vault Store and click Next.
d. Click Add to browse for the PST file that was created in Step 2 and click Next.
e. Choose the Select an archive for each PST radio button and click Next.
f. Select the appropriate Retention Category and click Next.
g. Select the Destination archive and Associated Mailbox for the user and click Next.
h. Select the appropriate Retention Category and click Next.
i. On the shortcut option window choose the No radio button to avoid duplicate shortcuts and click Next.
j. On the folder structure window select the root folder and Merged options and click Next.
k. Leave the default settings on the remaining boxes and click Close to complete the wizard
