What you need to do is find a cinema that still does 35mm (or is interested in doing 35mm) and then get them to book the film. It wouldn’t be hard to convince them to book Titanic as it ticks all the right boxes: it’s a family film (both kids and adults can enjoy it), it’s a good quality film being made in the later 90’s compared to lacklustre 80’s prints, it’s a popular movie that people love. A good place to start would be your local film and tv archive, find out from them if there are any local cinemas they loan or hire prints to for exhibition and then go from there.