Zoho CRM <> Zoho Desk Account Sync

I have had custom fields in Zoho CRM for a time and would like that data to sync to Zoho Desk. However, since the accounts are all synced to Zoho Desk already, the newly mapped fields are not updating in Zoho Desk. Is there a way to force the sync to Desk? Currently, the only way I've been able to get this data to sync has been manually editing every single custom field in every single account within CRM, which is not only impractical, but could take months as we have thousands of accounts in CRM.

Is there a way to force this sync?