April would be Summer in many parts of Central and Southern India. Kashmir, Manali, Dehradun, Dharamshala etc would be great options. Or North-east - Sikkim, Manipur, Meghalaya would be ideal too.
Next month being summer you can travel to cool hill stations in India. Coorg
Lambasinghi
Ooty Kodaikanal
Mahabaleshwar Panchgani
Matheran
Shimla
Manali
Mcleodganj Darjeeling Nainital
Mussoorie Leh
Ladakh