1. A method for controlling regeneration within an after-treatment component of a compression-ignition engine, comprising: receiving a pressure drop index indicative of a decrease in pressure of an exhaust stream as it passes through the after-treatment component; receiving a flow rate index indicative of a rate of flow of the exhaust stream; calculating an initial estimate of accumulated particulate matter in the after-treatment component based on a pressure-based soot accumulation model, the pressure drop index, and the flow rate index; calculating a soot prediction error inherent in the soot model; calculating an adjusted estimate of accumulated particulate matter in the after-treatment component based on the initial estimate of accumulated particulate matter in the after-treatment component and the soot prediction error; comparing the adjusted estimate of accumulated particulate matter in the after-treatment component to a predetermined threshold associated with the after-treatment component; and initiating a remedial action when the adjusted estimate of accumulated particulate matter in the after-treatment component exceeds the predetermined threshold.