I think the best way to say it is: 1) If you go there, I will go there too. 2) If you are going there, I will go there too. I feel (2) is more natural, but both are fine. "If you will go there" is wrong because this type of "conditional" clauses should not be in the future tense. Conditional events expressed with "if", "when", "unless", "as soon as", etc. should be given in the present tense, as their futureness is obvious from the meaning of the conjunction as well as the clausal structure. For example, - When you get to LA, give us a call. (not "When you will get to ...") - If you fail this time, you won't get another chance (not "If you will fail ...")