The cautious solution is to run:

sudo apt-get install <list of packages kept back>. 

In most cases this will give the kept-back packages what they need to successfully upgrade.

You can run:

sudo apt-get --with-new-pkgs upgrade

It will install the kept-back packages. This has the benefit of not marking the kept-back packages as “manually installed,” which could force more user intervention down the line (see comments).

A more aggressive solution is to run:

sudo apt-get dist-upgrade

This will force the installation of those new dependencies. But dist-upgrade can be quite dangerous. Unlike upgrade it may remove packages to resolve complex dependency situations. Unlike you, APT isn't always smart enough to know whether these additions and removals could wreak havoc.

So if you find yourself in a place where the “cautious solution” doesn't work, dist-upgrade may work… but you're probably better off learning a bit more about APT and resolving the dependency issues “by hand” by installing and removing packages on a case-by-case basis.