Wireless local area network (WLAN) IEEE 802.11 communication devices employ channel coding and automatic repeat request (ARQ), commonly known as hybrid ARQ (HARQ) type I, to provide robust and reliable communications. For emerging use cases like industrial IoT and machine-to-machine (M2M) communications, the performance of HARQ type I is getting insufficient, especially in adverse channel conditions with low link budget. For this reason, this paper investigates enhanced HARQ operation for WLAN by soft combination of retransmissions. We first outline three different implementation variants of HARQ with soft combination, discuss their adaptation to WLAN physical layer and perform a rigorous analysis in terms of achievable reliability, throughput as well as latency. It turns out that for high reliability applications, HARQ type III (T3), in which retransmissions use codewords (CWs) with new parity information, performs best, whereas for high throughput application HARQ type II with incremental redundancy (IR), in which retransmissions consist of new parity information only, is more suitable.