Triple H VS Lesnar 2 would be pointless. Lesnar lost his big comeback match to John Cena, he needed to gain some credibility (especially if WWE plans on having Taker VS Lesnar at Wrestlemania 29), and he gained that credibility by defeating Triple H at Summerslam. Lesnar has nothing to prove to HHH, and if a second match actually happened, I'm pretty sure HHH would go over. It's the only logical outcome, because there would be no point in having Lesnar beat HHH for a second time.
Triple H has piled up more than enough accolades during his WWE career. After all, he took The Undertaker to the limit at Wrestlemania three times (fuck you, WWE, I do remember Wrestlemania 17), the man is a certified legend, and HHH is a thirteen time world champion.
But WWE is putting a lot of effort into Triple H's possible retirement storyline, so seeing a second match between these two wouldn't shock me. Lesnar and Triple H delivered a good match at Summerslam, but I'm not anxious to see another encounter between these two. I enjoyed the match, but in the end, Lesnar VS HHH really didn't live up to the tremendous hype. Lesnar got his first win, he can move on to other feuds, and Triple H can still fulfill the requirements for the non-wrestling side of his character, so do we really need to see these two go at again? Also, Lesnar VS HHH 2 wouldn't have the feeling of a "must-see" attraction anymore.