Simple Q&A Pathfinder (By RAW) I

[Zejety]

Q71 Q72

Replacing and Copying Spellbooks

A wizard can use the procedure for learning a spell to reconstruct a lost spellbook. If he already has a particular spell prepared, he can write it directly into a new book at the same cost required to write a spell into a spellbook. The process wipes the prepared spell from his mind, just as casting it would. If he does not have the spell prepared, he can prepare it from a borrowed spellbook and then write it into a new book.

emphasis mine

Which procedure does the first sentence refer to?
The paragraphs "Spells Gained at a New Level", "Spells Copied from Another's Spellbook or a Scroll" and "Independent Research" from the same page?

Does that mean you will have to re-learn your lost spells from scratch (if you can't borrough a book containing them), for example by spending your 2 spells per levels?