The following articles describe the required steps to upgrade your Telerik Reporting projects.
Check all the official versions Release Notes between your current version and target new version. They describe any new features, fixes, breaking or dependency changes.
Install the new Telerik Reporting version as described in the Installing Telerik Reporting help article or using the Telerik Control Panel.
Upgrade all projects that use Telerik Reporting as described in Upgrading Telerik Reporting Projects.
Go through the Upgrade Path articles between your current version and target new version. For example if your project currently targets Q3 2013 and you want to upgrade to Q1 2014, you should review the Upgrade Path articles for Q3 2013 SP1 and Q1 2014. In the concrete example Upgrade Path Q3 2013 SP1 article is missing because no breaking or dependency changes are introduced in the Q3 2013 SP1 release.