Long-term stable operations of XeCl exoimer lasers depend considerably on the depletion of HCl. Our experiments have shown that the lifetime of such device can be extended significantly by adding appropriate amount of cheap donor gas HCl into the laser chamber made of epoxy resin pipe. In this way, more than 1.3×106 pulses were obtained by once filling Xe and Ar and then replenishing HCl at several appropriate times. For a repetition rate of 5.3 pulses per second and single-pulse energy of 100 mJ the laser was still able to operate normaly after working continuously for 54 hours. The maximum single-pulse energy of the laser was 160 mJ. The influence of the content of HOI on the output characteristics of the laser was also studied.