Does AWS Lambda allows to upload binaries separately to avoid re-upload
No, there is no way to accomplish this. Your Lambda function is always provisioned as a whole from the latest zipped package you provide (or S3 bucket/key if you choose that method).
I am new to AWS Lambda, I have phantomjs application to run there.
There is a python script of 5 kb and phantomjs binary which makes the whole uploadable zip to 32MB.
And I have to upload this bunch all the time. Is there any way of pushing phantomjs binary to AWS lambda /bin folder separately ?