Can I Convert My Existing Telerik Reporting Reports Into Telerik Report Server Reports?

Yes, you can.

Report Server works with declarative report definitions which are .trdx, .trdp, and .trbp files created using the Standalone Report Designer or the Web Report Designer. Such reports may be uploaded directly.

To upload compiled reports created with the Visual Studio Report Designer you need to first open the report library dll in the Standalone Report Designer and save the contained reports in declarative report format.