  We study a system of two electron spins each interacting with its small
nuclear spin environment (NSE), which is a prototype system of two electron
spin quantum dot (QD) qubits. We propose a way to counteract the decay of
entanglement in two-electron spin subsystem (TESSS) by performing some
manipulations on TESSS (the subsystem to which experimentalists have an
access), e.g. repeatable quantum projective measurements of TESSS. Unlike in
the quantum Zeno effect, the goal of the proposed manipulations is not to
freeze TESSS in its initial state and to preclude any time evolution of the
state by infinitely frequent quantum measurements. Instead of that, performing
a few cycles of free evolution of the system for some time $\tau$ followed by a
quantum measurement of TESSS with subsequent postselection of TESSS state (the
same as the initial one) produces quantum correlations in NSEs and also
restores the quantum correlations in TESSS. By numerical calculation of the
system evolution (the full density matrix $\hat \rho(t)$), we show that, in
contrast to the fast decay of TESSS entanglement on timescale of the order of
$T_2^*$, application of the proposed manipulation sequence gradually builds up
coherences in the entire system and the rest decay of quantum correlations of
TESSS may be significantly slowed down for specific cycle durations $\tau$ and
numbers of performed cycles.
