The level-up feature will recommend a new program. Level down would be used if your feel like the current program you are in is too challenging. Level up would be used if your current program is feeling too easy.
Let’s go through an example here:
Let’s say you are in Shoulder [P]rehab. You start working through week 1 and find the movements to be too challenging or intense. Level down would recommend you stop this program (progress would be saved) and go to a less intense program such as Shoulder Rehab.
On the other hand, if you are in Shoulder [P]rehab and your start working through it and find that its way too easy level up would recommend you move into Upper Body Performance level 1, a more intense and challenging program (progress on shoulder [P]rehab would be saved).
Hoping this helps clear it up, let us know if you have any questions on this!