Answer
There is not enough information to tell.
Work Step by Step
We know when the system does some work, then the change in the system's energy is given by
$$\Delta E_{sys}= \Delta K+\Delta U+
\Delta E_{th}=−W$$
So the increase of the system's potential energy while doing work could be in parallel with losing kinetic energy as well. Also, it could gain both kinetic energy and potential energy through this process.
And since the energy could be transformed to or from the system by doing work, so the kinetic energy could be transformed into thermal energy.
From all the above, it is obvious that we couldn't define what will happen to the system's kinetic energy.
Therefore, the right choice here is that $\text{there is not enough information to tell}$.
