Yes, edit the file /etc/apache2/sites-enabled/subdomain.domain.tld.conf and locae the the path to the SSL cert and key, which will be something like /srv/subdomain.domain.tld/config/ssl/sets/1/.
Change this to /srv/subdomain.domain.tld/config/ssl/current/ and it should be fine an pick up any changes to the cert when Apache is reloaded (which happens as part of the hooks for sympl-ssl).
The plan is that a later version of Sympl will simply default to using the config/ssl/current/ path, making this unnecessary, but it’s a workaround for now.