Can I convert my existing Hughesnet for Business plan to the Hughesnet Internet Continuity plan?

No, this option is not available at this time. You can always use ANY Hughesnet® satellite internet plan to back up your primary terrestrial broadband connection. If you are technically savvy, you can setup a router with two WAN connections and have it automatically choose your Hughesnet satellite connection during a primary failure. You can also do this manually by hand connecting your LAN cable from your primary modem to the Hughesnet satellite modem.