Menu: Data->Problem type->Transform...
This option can be found inside the Problem Type menu and is useful for updating a model from an old problem type to a newer one that is similar to the first.
When converting, it tries to maintain all the conditions and materials assigned to the geometry or mesh. Also, it tries to maintain the rest of the data.
It will typically be used when a problem type has been updated and it is necessary to reuse a model defined with the old version.