(Using Reflex XTR)
One night on the sim I wanted to hone my landing with a forward slip. Once I landed the plane, taking off and getting it lined up on final approach was taking too much time out of practicing my objective. I was able to set up the sim so the plane started at altitude and at flying speed. In other words once the plane landed (or crashed) the sim restarted with the plane flying on final approach.

For Reflex users go to “Simulation” then “Modify Sim Parameters”, then click on the “General” tab. Once there change “Launch Initial Altitude” and “Launch Speed”. Remember these are meters and meters per second. The numbers will be a preference of trial and error. If I remember correctly think I prefered the altitude at 50[m] and a speed of 20 [m/s].

Once I did this I was practicing forward slips one right after another. Before too long I was consistently doing very pretty slips with both left and right rudder.