But 2 months?? I dont think so because I already know most of the concepts of java
We tend to think that just knowing the concepts of Java is enough.
The actual exam is intentionally deceptive and it is not just about knowing the concepts. Its about acute application of those concepts.
The choices are so close sometimes, that unless you've practiced real hard with the examples given in KS & BB (the Bible of SCJP, I just can't thank the authors enough), you are likely to falter again.
I'd suggest digging deep into the topics you failed in.
Try out the examples given in the book, observe the output.
Again, go back, change the code, and then observe the output again.