  The paper deals with the theoretical consideration of surface
plasmon-polaritons in the graphene monolayer, embedded into dielectric with
spatially separated gain and losses. It is demonstrated, that presence of gain
and losses in the system leads to the formation of additional mode of graphene
surface plasmon-polaritons, which does not have its counterpart in the
conservative system. When the gain and losses are mutually balanced, the
position of exceptional point -- transition point between unbroken and broken
$\mathcal{PT}$-symmetry -- can be effectively tuned by graphene's doping. In
the case of unbalanced gain and losses the spectrum of surface
plasmon-polaritons contains spectral singularity, whose frequency is also
adjustable through the electrostatic gating of graphene.
