If you want RTR A license you need to pass both Part 1 and Part 2 .
Once you pass the exam you surrender the RTR P license to the WPC and get a new RTR A license with lifetime validity ( by paying the 10,000 rupee DD )
For those of you undergoing self study for the RT exams i recommend the following book .
But coaching atleast for Part 1 of the exam is still recommended
Sterling Book House - About Us