In most case once denied, the case is dead. Check the following examples:
http://uscis.gov/graphics/lawsregs/admindec3/B2/index.htm
http://uscis.gov/graphics/lawsregs/admindec3/b3/index.htm
In your case, if you can find a permanent position, you can file under EB1(b), which is considerably easier than EB1(a).
Good luck.