We generalize the formulation of Poisson-Lie (PL) T-plurality proposed by R. von Unge (2002) [6] from Lie groups to Lie supergroups. By taking a convenient ansatz for metric of the σ-model in terms of the left-invariant one-forms of the isometry Lie supergroups (C3+A) and GL(1|1) we construct cosmological string backgrounds, including (2+1|2)-dimensional metric, time-dependent dilaton and vanishing torsion, in a way that they satisfy the one-loop beta-function equations. Starting from the decompositions of semi-Abelian Drinfeld superdoubles (DSDs) generated by the (C3+A) and gl(1|1) Lie super bi-algebras we find the conformal duality/plurality chains of 2+1-dimensional cosmological string backgrounds coupling with two fermionic fields. In particular, the new backgrounds obtained by the super PL T-plurality remain conformally invariant at one-loop level. This work can prompt many new insights into supergravity and obviously has interesting mathematical relations with double field theory.