Living in Galut (unfortunately) I understand that the Chazal instituted a second day for the beginnings and ends of the Shalosh Regalim, and I keep this obligation. However, now that we know exactly when the Chagim, such as Succot or Pesach begin, is it a Bracha in vain to repeat the Shehechyanu on the second day since it is no longer a "new" Chag and is essentially an elevated Chol Hamoed from what I can tell. I am not a Rabbi so please forgive me for misinterpretations. Thanks you.
The Bracha is not in vain for this is what our Rabbis commanded us to do so. The additional day of Yom Tov is not an upgraded day of Chol Hamoed, but it receives its holiness from the power vested in Chazal and it is similar to a degree to the holiness of the first day. In order to appreciate the significance of the extra day, I will offer you some insights on the issue. The Gemara in Betza 4b already asked your question and answers the question by saying that we must upkeep the custom of our forefathers, because there may G-d forbid be decrees against the Jewish people throughout the course of exile and the computation may be forgotten, and as Rashi adds a 29 day month will be made 30 days and people may eat Chametz on Pesach. The Rambam writes this as halacha in n Hilchot Kiddush hachodesh 5:5, and states: However, the Rabbinic ordinance is to continue to follow adherently the custom of their forefathers. Therefore any place where the messengers of Tishrei would not reach on time at the time when they were sent, should keep two days even in our time just like it was done when they the inhabitants of Eretz Yisrael would determine the new moon by observation. You may ask though why is this observance still needed. Rabbi Samson Raphael Hirsch zt"l in his commentary to Shemot 12 offered the following explanation: The second days appended to each Festival remind us of the original "Kiddush al pi Re'eya” (proclamation on the basis of actual physical observation of the New Moon)… The institution of the second days for each Festival had its origin in those better times long ago when our community still had its spiritual center [in Eretz Yisrael] and its duly constituted spiritual authorities and they were required to wait in anticipation of their instructions in regard to the time of the holidays. The very expectation [of the exiled communities] enabled them to see themselves as limbs of a greater national body and their holidays as freely established ones. It is therefore entirely true that, for Israel in exile, only the observance of a second day will insure the hallowed, truly Jewish character of the original. Rav Tzvi Yehuda Kook zt"l (in a letter written in 1914, in the book "Tzemach Tzvi pg. 74) writes that the second day kept in Chutz la'aretz is to impress upon the inhabitants Chutz la'aretz that there are no "bet din smuchim"= officially ordained Rabbinical courts in chutz la'aretz, no making of leap years in Chutz la'aretz, and no sanctification of the New moon in Chutz la'aretz. He remarked that only the recognition of the centrality of Eretz Yisrael and its ability to sanctify the holidays is what gives the 2nd day in exile any significance. Therefore any belittling of that recognition and consequent disregard for observing the 2nd day constitutes "Kefira" ,lack of belief in Hashem. Since it is only that constant recognition and longing we shall attain the true holiness of the one day we keep in Eretz Yisrael. Rabbi Eli Munk zt"l ( in the World of Prayer Part II pg. 136), seemed to sum it up in short: Our brethren in exile need two days to attain spiritually what we in Eretz Yisrael attain in one day. Therefore, by your adding to your question "Living in Galut (unfortunately)", I think you have a better understanding than others who don’t see living in Galut as unfortunate. L'shana Haba'ah B'yershulayaim Habnuya. Next Year In Jerusalem