K.Rohit,
1. This kind of problems refer to the B/S and C/S architecture. Change the app to ASP.NET can be convenient to the government manage tickets and customers book the tickets online on any computers with the Browser. It is certainly a good choice.
2. With the C/S architecture with the VB.NET application, you can change the source database and make each of the client access centural SQL database remotely. In order to to that, you need to give each of the clients power to access the central database. Sometimes it may cause the security problems.
3. In the long run, it is the trend that everybody is able to book the tickets online. So my suggestion is to change the VB.NET app to ASP.NET with B/S architecture.