Is there such thing as too many follow-up emails to a professor? I worked with my professor on a project for two months at the beginning of this year. After a while, I finished writing up the paper and sent it to him to check. He didn't reply. I've sent 5 follow-up emails within the span of 3 months after that with no reply. I am afraid to send another follow up email (the last one was a month ago) because I don't know whether he wants to continue with this project anymore. 
Should I just give up? or start sending more follow-ups but at a higher frequency?
Email is obviously not succeeding, so contact him another way.  Phone, postal mail, visit his office, etc.  You may also contact his department chair and ask if they know of any reason why he wouldn't be answering emails.


  I don't know whether he wants to continue with this project anymore. 


Even if that's the case, you have every right to be told that directly.  Ignoring your emails would not be an appropriate professional way for him to communicate that to you.