The teachings herein disclose methods (600, 700) and apparatuses (36, 50) for dynamically rescheduling retransmissions from a selected Hybrid Automatic Repeat reQuest, “HARQ”, process, based on temporarily remapping the selected HARQ process to one or more subframes (12) that are by default scheduled for another HARQ process running synchronously with the first HARQ process. One advantage of dynamic rescheduling is that a retransmission for a given HARQ process can be accelerated in time, as compared to when the retransmission would occur absent the remapping. In another advantageous aspect, in at least some embodiments, the control signalling (20) for dynamic rescheduling is included in the Downlink Control Information, “DCI”, used to send scheduling grants for the HARQ processes, such that dynamic rescheduling uses control signalling (20) that is compatible with existing scheduling grant signalling.