We investigate Bloch oscillations in a lattice system featuring a momentum gap ($k$ gap), where in-gap modes exhibit exponential growth or decay. We demonstrate that the interplay of $k$-gap amplification, attenuation, and interband interference gives rise to a critical regime, where the wave packet alternates between the growing and decaying channels, forming a period-doubled oscillation with globally stable intensity under critical driving—a phenomenon we term self-balanced Bloch oscillations. This self-balance arises from phase-accumulation-dependent selection of the $k$-gap channels during band traversal, as confirmed by numerical simulations and spectral analysis. This mechanism, broadly applicable to $k$-gap-engineered systems, not only enables intrinsic stabilization beyond mere amplification but also offers a powerful route for controlling wave propagation in time-varying media and non-Hermitian physics.

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• Light propagation, transmission & absorption
• Photonics
• Non-Hermitian systems
• PT-symmetry