Some modifications of the formula for calculating the electromagnetic pion-mass difference are proposed on the basis of the chiral-symmetry-restoration phenomenon at high energies and the operator-product expansion of quark densities for vector (ρ) and axial-vector (a 1) meson fields. All calculations are performed through taking into account higher meson resonances in the vector and axial-vector channels. It is shown that the inclusion of only the first ρ 0 and a 1 radial excitations improves the results of the calculation for the electromagnetic pion-mass difference in relation to the known ones. The electromagnetic ρ-and a 1-meson decay constants and the constant L 10 of the effective chiral Lagrangian are estimated with the aid of the generalized Weinberg sum rules.