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We present an experimental method where using a series of shaped longitudinal plasma density profiles we increased the mean electron peak energy more than 50%, from 175\u2009\u00b1\u20091\u2009MeV to 262\u2009\u00b1\u200910\u2009MeV and the maximum peak energy from 182\u2009MeV to 363\u2009MeV. The divergence follows closely the change of mean energy and decreases from 58.9\u2009\u00b1\u20090.45 mrad to 12.6\u2009\u00b1\u20091.2 mrad along the horizontal axis and from 35\u2009\u00b1\u20090.3 mrad to 8.3\u2009\u00b1\u20090.69 mrad along the vertical axis. Particle-in-cell simulations show that a ramp in a plasma density profile can affect the evolution of the wakefield, thus qualitatively confirming the experimental results. 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