R4J Cloud supports requirements reuse via the copy and paste operation. Requirements in a project tree, including their folder structure, can be copied to a different folder of that project or to a folder in a different project. (This works also for any kind of issue type, not only for requirements.)
To execute the operation:
Select a folder or requirement in the project tree and select Copy in the context menu.
Select the target folder in the same project tree, or in the tree of a different project, and select Paste in the context menu.
If the copied item is a requirement, the result is a copy of it and any child requirements in the target folder. If the copied item is a folder, the result is a copy of the folder and its entire contents in the target folder. The contents include the requirements (as well as any child requirements), and any subfolders and their requirements, as deep as the folder hierarchy extends. Attachments are also copied. While Sub-tasks, Issues under Epic, Linked issues (are only copied when they are in the tree).
To copy an entire project tree into a new project, simply create the new project in Jira, activate it for R4J. Select and copy the requirements and folders under the root folder of the first project then paste them to the root folder of the new project. This practice could be useful if, for example, you have a template requirements project and want to ensure that new projects start from that template.