What were the reasons for the re-emergence of serfdom in eastern europe in the early modern period?

Shortage of labor, economy, land lords needed to revive the economy somehow, options are limited, the serfs have nowhere to go. The nobles were more willing to be limited because they didn't want another war or another invasion. The monarch gives the lords autonomy over their lands in return for recognition as the monarch.

Interpreting the results of his experiment : )