Laravel 5.1 session updating randomly

I have one issue regarding session of laravel 5.1. I have written a code which will give 2 ajax call simultaneously. In first ajax call i am retrieving data and inserting paramertes into session. And in the response of first ajax, i am giving second ajax call to only update the session for second ajax parameters. But i am facing problem for session is that, it sometimes updates session and sometime fail to update the session. I am storing these parameters into session because on page reload, i am using these parameters again. Any help will be appreciated. Thanks

via Chebli Mohamed