Like Uto said, the idea behind changing capital is not just for the sake of changing it. The motive is to de-centralize the economy of the country. And that can be achieved by many other ways than just changing the capital. The initiative should start from government level to create an attractive incentive in areas such as Biratnagar and Hetauda so that the investors are more likely to invest in these areas. Looking at our southern neighbor, they have so called "economic zones" in cities like Hyderabad where investors get years and years of tax break for just opening their office there and building a community of its own.
If we do so in these already industrial zones there will be a lot of outflow of companies and jobs to these areas thus developing the overall economic condition of the local zone.