That sentence is technically incorrect without the pronoun. However, if you were talking with someone, they might leave out the "I'll". You can sometimes drop the pronoun in colloquial speech if it's understand who the subject of the sentence is. For instance: "See you tomorrow" is understood to mean "I'll see you tomorrow". Hope that helps, Adam

You must have a pronoun or the sentence will be incomplete. I can write that sentence a 999999999- different ways. We will fix you breakfast. George will fix you breakfast. She will fix you breakfast. The pronoun lets you know who the subject is. Who is the one fixing your breakfast. So simply put. I'll fix you breakfast before your exam is correct. I do not know what you mean by the pronoun being rejected.