You can upgrade using apt (this does take into fact that your local version of dradis is older than the one in our repos). However if you are wanting a newer package that is not in the repo then you are really on your own. Most tools will have plenty of documentation on how to install and or upgrade them. Dradis not being an exception to this.
A better idea would be to suggest it in the tool request forum if the version available is different then the one in the repo.