Renouvellement visa ?

Bonjour

I am not sure how nuch time to spend in SR ? I have time on my hand . Is it easy to renew a 4 weeks visa ? I want to fly from Trivandrum , beggining of December , I guess a return ticket would be cheaper but going one way would give me freedom . I am not even sure if one way ticket is possible ? What do you think ? One month or two in SR ? Enough to do for 2 months ? Can I buy a ticket returning two months later , even if you only get 4 weeks visa on arrival ? The problem is that I feel I must make my mind about wether I am going to love it before even going there , because of the buying ticket business !! I love India , I am now in India for the fith time . Thanks for any help .