If the requisite amount of dough is made that would require taking challah if it were baked in the oven, should one take off challah with a bracha if she intends to deep fry the dough instead?
No, one should not recite a bracha. The Shulchan Aruch (YD 329:3) rules that thick dough kneaded to be boiled (which is what deep frying is) is exempt from Challah. The Shach notes that some opinions don't care what his intentions are when kneading, and if it is a thick bread-like dough it is obligated in Challah from the time of kneading. The Pitchei Teshuva there also notes a possible opinion of Rabbeinu Tam who argues on the Shulchan Aruch. Thus both recommend separating Challah anyway out of doubt, but to refrain from saying the bracha.