Poorly plant

Had this plant since my 22 year old son was in primary 1. It started off as a tiny cutting from school that just kept growing. Living in the laundry room of our last house was a brilliant hot and humid environment which resulted in a strong plant.
Since moving here in August of last year it has lived in the sitting room which faces much more north and is cooler with less sunlight. Poor plant has been struggling.
Today we replanted with fresh soil and moved it to the patio door which is really bright, hot and sunny. Everything crossed it recovers and become that strong healthy plant again.