Hi,
Install a new 7.1 or 8.1 Spectrum Protect Server and do server to server communications to export the data to the new server. Move clients to the new server after the export/import.
Lookup export node: Export NODE
You can do upgrade from 5.5 to 7.1 but this is a more complicated process. Starting clean with 7.1 or 8.1 is recommended. I have done export from 5.5 to 7.1 servers, though it is not a supported, it works great. Do perform a test restore afterwards to verify things work as expected!
Kind regards, Groetje,
Marcel