There is no easy way to migrate from one db platform to another. Sqlite is ok for low traffic sites but it does not scale for high traffic, beter to use a more robust db like MS SQL. The only advantage of Sqlite is easy deployment since it requires no database server software and just uses a file based db, but it can't typically be used in shared hosting because it can't be used under Medium Trust security policy which most hosts enforce. Whereas robust db platforms have a connection pool, Sqlite really only has a single connection so each bit of code that access the db must wait for its turn to use the connection.
Hope it helps,
Joe