Go to google flights, search IAD, DCA to BTV, MHT. You will see that UA is the only one that offers non-stop IAD-BTV, all others require a stop. AA offers non stop from DCA to both BTV and MHT. Price is around $250. They both offer several options a day, you need to determine what will work for you as far as timing goes. Once you determine which carrier to go with, you could check with them regarding activating your expired account. Depending on how many miles expired and the cost, it might we worth it.