Long-Range Frequency Hopping Spread Spectrum (LR-FHSS) is a recent IoT modulation technique designed for communication between low-power ground end-devices and Low-Earth Orbit (LEO) satellites. To successfully decode a frame, an LR-FHSS gateway must receive at least one header replica and a substantial portion of the payload fragments. However, the likelihood of LR-FHSS header loss increases with the number of concurrent transmissions. Moreover, Doppler effects (such as the Doppler shift and the Doppler rate) distort the signals the satellites receive. This paper investigates advanced receiver techniques for recovering LR-FHSS frames with lost headers characterized by significant Doppler effects. This paper’s main contribution is specifying and validating a novel LR-FHSS receiver model for space–terrestrial integrated IoT environments. Obtained simulation results prove that our enhanced LR-FHSS receiver can decode a significant portion of the missing frames, improving the overall throughput achievable by using the legacy LR-FHSS receiver.