An infusion pump device (10) comprises a primary reservoir (11) for the liquid medicament, a pump (14, 16) with a secondary reservoir (14) that is able to retrieve liquid medicament from the primary reservoir and to subsequently dosing said liquid medicament from the secondary reservoir in one or more portions of adjustable volume (V dose,i ) to a downstream conduit (25, 28), and a control unit configured to control the operation of the infusion pump device. For metering the multitude of portions (V dose,i ) the control unit causes the infusion pump device to carry out the following steps: (a) determining a maximum refill level (V C,max ) for the secondary reservoir (14), based on given external parameters, wherein the maximum refill level does not exceed the maximum capacity of the secondary reservoir (b) filling the secondary reservoir with liquid medicament from the primary reservoir to the maximum refill level (V C,max ) (c) metering and conveying the multitude of portions of liquid medicament to the downstream conduit (d) if the secondary reservoir (14, 16) becomes empty, refilling the secondary reservoir as in step (b) and continuing with step (c).
