'Lower' is correct. The station first rotates so that the engines of the Soyuz are pointing in the direction of travel, then the engines are fired for a short period in order to induce a negative acceleration of approximately 1m/s, which in turn causes the orbit of the station to decay slightly (a.k.a. a 'lower' orbit) in order to avoid objects in or close to the current orbit.
After the danger has passed, the direction of the Soyuz is reversed so the engines are pointing back along the path travelled, and a longer burst accelerates the station again, thus restoring the original orbit of the station.
This was last performed in August 2008, ironically also to avoid orbiting satellite debris.