I think, the OP wants to connect the invalid linebreaks/paragraph breaks. If that assumption is correct, I don't think there is any possible way of coercing Word to do that while exporting. But there are some tools available to do some of the heavy work (but not necessarily for free):
TransTools for Word has an "UnBreaker" tool. It lists all the linebreaks, which are (probably) not valid, and the user can go through the list and mark those he thinks should be rectified. -
(TransTools is a suite of VBA-macros, and as such rather slow. So it should be tried on a small subset of the file in question first to see if it's usable)
Pepito Cleaner (for OpenOffice/Libreoffice) has something similar.
(It's broke on LibreOffice 6.1, but should work on 6.0)
If the PDF is something with a text-layer, the OP might try Softmakers
FlexiPDF (it must be the Pro version!) to export the textlayer. It does a hell of a job figuring out the correct paragraph breaks. It has a somewhat steep price (I've never regretted buying it, though), but another software vendor, AShampoo, has leased it from Softmaker and sells it sometimes for 20$ or so.
Just some 0.02 cents suggestions - hope it might help.
Regards,
Kim