I was wondering if it is possible to save survey responses before a survey's session expires.

I've gone through this  thread , and their solution to avoiding session timeouts was to increase gc_maxlifetime from the default 24 minutes.
I've also come across Denis Chenu's HeartBeat , but I'm concerned about sessions never ending with this.
These are good solutions, but I also want the responses saved.

My LimeSurvey set up:
- Currently using file based sessions
- CentOS running Apache and PHP-FPM
- Postgresql database

Responses are saved as soon as the respondent moves to the next "page", so whenever they click the button to continue or submit.

So all responses up to the current "page" are already saved to the database. Of course, if you run a survey "all on one page", then this doesn't help, but then I don't see any other option to save these responses from within the normal Limesurvey behaviour anyway. If you use "group by group" or "question by question" display of your survey, only the responses to the current question on the current page would be lost.