You could try going to Gokarna which has a lot of kids-friendly beaches and not a lot of people there unlike Goa. You can finish going to all the places there in 2 days and take rest for a day there on the beach by camping out with your family. Or you could also try going to Kodaikanal but be careful, you might want to go by your car there because there's not of lot of vehicles to hire and it's super cold in Kodai right now. Or you could try and go to Hampi. There's a travel company that manages trips from Bangalore to Bangalore and is budget friendly too, maybe check them out and see the locations you could go to(FYI they're all treks and camping trips, not sure if you're interested in them), website address is www.plantheunplanned.com. Hope you have a amazing and a safe journey with your family :")
Try Kodaikanal. It is also a small hill station, much like coorg n ooty, which I see that you have already visited but as you mentioned that you have a toddler, then you can take a good resort and enjoy in the cool weather there.
Also, you can do cycling and horse riding around the lake.