If new face is introduced as Riddhima then it would be silly to show Shilpa
in the flashback, i mean two faces of one person.
So probably what make sense is that they will introduce new character
who would fall in love with Armaan and try to woo him
and Armaan will remember his Riddhima in the flashbacks.
But then what will they do with old Riddhima
either send her away somewhere
or maybe kill her character with some kind of encounter with the decoits.
I dont think creatives will let go of the old scenes
and they also know very well that viewers will take some time to accept new face
so hopefully i dont think they will merge two faces in one character.
that would be utter confusion