You don't need to upgrade if you don't want that your SIP users to have access to their profiles and manage it.
Be sure you make backups of Kamailio and Siremis databases. Also, you can backup the directory where Siremis was installed.
Some notes and tips about upgrade of an existing v3.2.0 installation:
your Siremis users will be lost, 3.2.1 has a new set of Siremis user roles
delete database siremis (e.g., from mysql cli: “drop database siremis')
replace the content of previous Siremis installation directory with the content of Siremis v3.2.1 (or start a new fresh installation following the guidelines for v3.2.x)
be sure the file 'siremis/install.lock' is removed (if exists)
access the Siremis
URL and do the installation wizard again
when setting the database attributes, be sure you don't select 'Update SIP DB' checkbox
finish the installation wizzard