Ok putting aside our likes and dislikes for Armaan/Purab, I don't see any good reason why Jassi shld go for a makeover unless something drastic change is planned in the future as of now there is no need for Jassi to go for a makeover.
It will be really ridiculous if she goes for the makeover for Purab since he is already ready to accept her the way she is. Also since she has now decided to get married to Purab no need to change the look for armaan either. What difference does it make?