Can the pcp package be updated to a newer version

Ubuntu is no rolling release. This means that packages in a certain Ubuntu release usually stay at the version that was current when that Ubuntu release was published. Newer versions of the packages usually are only provided with newer Ubuntu releases.

Ubuntu trusty was published in 2014 and provides pcp 3.8.12
Ubuntu xenial (published 2016) provides 3.10.8
Ubuntu zesty (currently in development for publication in April 2017) will probably provide 3.11.7 (or even higher).

Updates to packages in older Ubuntu releases are done only for specific reasons (e.g. important bug fixes or functional improvements), see https://wiki.ubuntu.com/StableReleaseUpdates

I see the following options for you:
1. install an updated version from a PPA (see https://launchpad.net/ubuntu/+ppas?name_filter=pcp for candidates, at least two of them provide 3.11.4 for trusty)
2. Create a PPA of your own (with whatever version you want) or
3. build that package from updated source on your own system
4. create a bug report that the existing version be updated (likelihood of execution depends on the importance of the changes)
5. upgrade to a newer Ubuntu release

If you report a bug and the bug and security fixes are significant then the package will be updated sooner rather than later.

Ubuntu is not a rolling release distribution so packages are left if there is no significant reason to upgrade it. Packages are not updated just because a new version is released