A taxi ride from Juanda Airport (Surabaya) to Kediri costs around Rp200000-Rp250000.
There are some trains with Kediri Satation as one of its stop. Here is the list:
Note: Economy class is not airconditioned and are not recommended. Business class is also not airconditioned, also not recommended, use it only if you cannot get the executive class. Executive class is comfortable and air conditioned.