Consider to do a 'apt-get dist-upgrade' or a 'apt full-upgrade'
Google will tell u the difference between upgrade, dist-upgrade and
full-upgrade;)
>
> In theory upgrading should do it, but in practice, some packages get added
> and thus aren't there to be upgraded.
Note: all packages installed with apt will be upgraded. But, there
might be other differences between 2016-05-13 and 2016-05-31, namely
other packages installed...