If you bought the pass at Thorpe as far as I know you need to get it re-printed there, but seeing as Thorpe Park is closed, and obviously other merlin attractions are open thats an interesting one, if I was you id give the annual pass team a ring and explain youve lost it and you wanted to use it on the london attractions and see if there able to help arrange a reprint at one of the london attractions. There number is 08444 77 44 44
If you do so, let us know what they say id be quite interested on that one as ive always thought having to get it re-printed at the attraction its bought at abit of a limitation.