What is his "usual" therapy based on? I would see about getting advice from a Bobath Pädiatric qualified physio. There is a center in India: The Indian Institute of Cerebral Palsy (IICP) Home Page.
Additional Comment I forgot:
may have clicked on the wrong link there, the cerebral palsy center may of course have all sorts of ways of treating CP and not only Bobath! I took a look at it again!