I have Niederlassungerlaunbis and I will be going to India for one year for studies. So, I have deregistered(Abmeldung) myself. I have also cancelled my health insurance. I would like to know whether my Niederlassungerlaunbis will remain valid if I visit Germany for 1-2 days every 6 month.

You should go to the Meldamt and explain your case. I think there is a document exactly for these cases where it is specified that you will be out of Germany of a certain period of time and will be coming back. This will allow you to come back. I don't remember the name of the document but the procedure exists. 

I went to local Alien office(landratsamt) and explained my case. They are demanding a proof that I will pay insurance for the entire duration and I have enough money in my bank account. So, I was wondering whether my Niederlassungerlaunbis will remain valid if I visit Germany once every 6 month for 2-3 days

Have a read through this.

http://www.gesetze-im-internet.de/englisch_aufenthg/


I would suggest you ask the Ausländeramt for information in this regards. Often times people in Landratsamt don't have the latest information.

Hi,
Few points to keep NA valid during your stay out of Germany:
1. In your case, please provide the proof of your studies in India and it's duration to the ABH and seek a written letter (I will post the document name soon. have to check my past folders...)
2. Keep the Health Insurance on 'Anwartschaftszeit'. You will pay the minimum to keep it active for the NE validity
3. If you have the above two satisfied, you can do Abmeldung and do not need to come for 1 or 2 days to Germany. Coming for 1 or 2 days in 6 months wouldn't keep your status live. If you stay more than 180days in a calendar year, it will help.
Hope this helps..

A quick update and a happy closure:
I emailed to my Visa officer at Landratsamt(Allien office for Unterhaching, equivalent to KVR for München) with a detail description of my case. She called me up a couple of days later and asked me to visit Landratsamt with a proof of my course. Today I got the letter which states that I can come back to Germany within one and half year(1 year course duration + 7 months grace period for internship). She did not ask for Insurance or anything else. Thanks all for your suggestions.