There was a very popular TV serial in India called Dill Mill Gayye where this sort of thing happened. It's a love story involving a group of young doctors interning at a hospital.
The main leads were Armaan Malik played by Karan Singh Grover & Riddhima Gupta played by Shilpa Anand/Jennifer Winget/Sukriti Kandpal.
Shilpa Anand playing Riddhima, the female love interest of Armaan Malik was recast due to her on-set tantrums & demanding a fatter paycheck after her popularity & fame. The character was played by Sukriti Kandpal for a short period. The character was recast again due to the lack of good acting skills & played by Jennifer Winget till the end of the show.
But at a later point in the show, a new character was introduced, namely Shilpa Malhotra, played by Shilpa Anand to add a love triangle between Armaan & Riddhima.
The move to bring back Shilpa Anand & cast her into a different character was made to salvage falling TV ratings & bring back some loyal admirers of the said actress.