Complex conjugate and IFFT
I'm not sure what you're getting at with "reflection" or "striping," but you want to duplicate your data points such that the frequency-domain signal (the input to the IFFT) is conjugate symmetric. That means, for $N$ even:

$$
X[k] = X^*[N-k], k = 1, 2, \ldots, \frac{N}{2}-1
$$

Note that $k$ is zero-based; the first element in the vector is $X[0]$. The above indicates that you do not duplicate the zeroth and $\frac{N}{2}$-th elements in the input vector. This relationship is based on the periodicity of the discrete Fourier transform; the first half of the frequency-domain vector corresponds to "positive" frequencies covering the angular frequency range from $0$ to $\frac{(N-1)\pi}{N}$. The second half covers from $\pi$ to $\frac{(N-1)2\pi}{N}$, which, taking advantage of the $2\pi$ periodicity in the frequency domain, is equivalent to $-\pi$ to $\frac{-2\pi}{N}$. In order for the frequency-domain vector to have conjugate symmetry, then it can be easily shown that the above relationship must be true.

Speaking to your original goal of converting a spectrogram into an audio signal that sounds meaningful, there's no guarantee that what you get out will be in any way pleasing. As was pointed out on Stack Overflow, the spectrogram has no phase information; the method suggested there assumes the phase of each frequency-domain bin is zero (so the conjugate operation shown above is superfluous). While the human ear isn't terribly sensitive to phase distortion in audio, you might have to do something else depending upon exactly what you're hoping to achieve.