Methods of process control are needed in order to advance additive manufacturing technology towards widespread commercial use. Here an optimal repetitive process controller (RPC) is developed for controlling part height in laser metal deposition (LMD), an additive manufacturing process in which metal powder is blown into a melt pool and parts are built in a layer-by-layer fashion. As with many additive processes, the geometry of the printed part depends not only on process parameters (laser power, table velocity, etc.), but also on the dynamics of the material addition process itself. The process is modeled with 2D dynamics, combining inlayer dynamics and layer-to-layer dynamics. The in-layer dynamics describe how material is distributed within the melt pool while the layer-to-layer dynamics describe how the heights of previous layers propagate through the part. This modeling framework allows for the design of an RPC. An optimal RPC is designed by using a lifted-system representation of the 2D dynamics and solving a quadratic cost function. The controller is implemented in experiment and the control performance is observed for different weighting parameters.