Hello strarsis,
One thing that you might try (no guarantee, I don't think I've tested it)
to recover Lensfun parameters is to load a project file (.pto) from the
earlier version in which you used lensfun lens parameters, then in Photos
tab, right mouse select an image and choose 'Lens > Save Lens parameters
to Lens database'.
Another, more time consuming, approach is to shoot suitable test images
and use Hugin Calibrate lens to generate the necessary necessary lens data
for Hugin-2015.0.0.
Cheers,
--
Regards,
Terry Duell