Consider the triple $V=l^1$, $H=l^2$, $V^*=l^\infty$. However, the closure of $l^2$ with respect to the $l^\infty$-norm is $c_0$, which is a closed and proper subspace of $l^\infty$. Hence, the embedding $i^*$ fails to have dense image. This proves that there is some non-reflexive $V$, where the claim fails.