Modelling error can be the cause of bad performance when optimal feed-rate profiles computed for a particular model are applied to the actual plant. This paper suggests the modification of the input trajectory from batch to batch, by using information from previous batches to modify the trajectories that are applied to the subsequent ones. The proposed approach does not require the remodeling of the process, but instead it redetermines the input profile directly, so that a steady improvement is accomplished from batch to batch.