Three phenomena limit the acceleration length in a laser-plasma accelerator: diffraction, pump depletion, and dephasing. Various strategies can be used to mitigate them, but they are often incompatible. Here we discuss several approaches to increasing the beam energy: the rephasing technique, which extends the effective dephasing length, the acceleration in a laser-plasma waveguide, which prevents diffraction, and finally a dephasing-less, diffraction-free acceleration scheme.