Regarding gratuity previous 5 year & current 5 years

You are entitled for gratuity, the reemployment being just a sham.

More more informed discussion, you may post the query at citehr.com

You are a contractual employee for specific time, 

However, Payment of Gratutity Act, 2018 covers private sector employees as well which is:

This amendment has aimed to ensure harmony amongst employees in the private sector and in Public Sector Undertakings/ Autonomous Organizations under the Government who are not covered under CCS (Pension) Rules.

These employees will be entitled to receive higher amount of gratuity at par with their counterparts in the Government sector. An employee is entitled to receive gratuity if he has rendered continuous service for at least five years with an organization and usually given at the time of retirement under certain terms and conditions.

This gratuity is payable to the employee on his superannuation, or on his retirement or resignation or in case of Death or Disablement caused due to accident or disease.

It appears that your contract was renewed from time to time (which is a very common practice by the management) only to deprive you from having a continuity of service and getting all statutory benefits including gratuity. This is nothing but a sham contract and only a paper arrangment and is void. The benefit of labour laws will go in favour of the employee. If there is no actual break in service then you are entitled to gratuity for your entire tenure irrspective of whether contractors were changed or not. Even principal employer may be held liable for payment of such statutory compliance.