Launched in 2009, Kepler is a NASA space telescope that has detected over 2,000 planets around other stars. Since the dates of these initial discoveries, a large effort has been made to reanalyze some of these exoplanets with larger datasets and more sophisticated methodologies. Of particular importance are the so-called circumbinary planets, or exoplanets that orbit more than one star. To date, about a dozen transiting circumbinary planets have been discovered. Here we present improved dynamical parameters for the following four circumbinary planets: Kepler-16b, Kepler-34b, Kepler-35b, and Kepler-38b. As opposed to the photodynamical models used in the discovery papers, our models include apsidal precession due to both General Relativity and tidal forces. Additionally, we make use of ground-based data for these systems.