Both VRL and 3DV files are based on VRML - Virtual Reality Modeling Language, so it should be easy enough to convert them between each other using programs that support these file types. There do exist even dedicated 3D converters like 3D Object Converter, that should be able to help you with this task.
Convert VRML virtual world file to 3D VRML world file.
We have found 2 software records in our database eligible for .vrl to .3dv file format conversion.
Microsoft Windows software - convert vrl to 3dv on Windows
A family of 2D/3D CAD software products for Windows
Convert from vrl file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned vrl to 3dv. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
3D viewer and converter with huge file type support