Umbrella plant leaf drop...help

My lovely 40 year old Umbrella plant is shedding lots of leaves, yet producing new shoots. As you can see it's almost 6ft tall. I repotted it about two years ago and removed a cutting which is thriving but also loosing the odd leaf. Any help or advice would be appreciated. TIA

 

Stuck in a corner it may be stressed due to a lack of light and to cold. It also might like to be misted occasionally.

 

Lower leaf loss is probably normal although as long as they go yellow first.

It probably is growing upwards in to darkness, if you see what I mean, which is not really how plants would grow in nature.