HONGKONG and Shanghai Hotels has no immediate plans to replace its managing director, Mr Hanmer Webb-Peploe, who retires at the end of this month. The Peninsula Group director of public relations, Ms Lynn Grebstad, said there were no plans at the moment to fill the position. Mr Webb-Peploe's five-year contract ends this month. He has decided not to renew his contract and will return to the United Kingdom for family reasons. ''My wife and I are naturally extremely sorry to be leaving a place in which we have spent 101/2 very happy years,'' he said. ''We are, however, looking forward to being in the United Kingdom again and closer to our three sons, two of whom are at university and one at secondary school.'' Mr Webb-Peploe leaves the company at a time when it has seven major projects in various stages of development in the territory and in Thailand and Vietnam, in all of which he has played an active role. Among them are the 30-storey tower extension of The Peninsula in Hongkong, which will be completed next year; The Peak redevelopment; three joint-venture projects in Bangkok, including the Peninsula Bangkok; and the International Burotel in Ho Chi MinhCity. During his term, the Peninsula Group went into North America with a 20 per cent acquisition in the Peninsula Beverly Hills in 1991 as well as the acquisition of the Peninsula New York in 1989.