step 3.1 : Give the user the choice to choose the current level he will play.

 Give the user the choice to choose the current level he will play.
This can be a dropdown menu or anything you want.
The available levels should be the levels he already passed.
e.g. if the user is in level 5, he can choose level 1, 2, 3, 4, or 5 from the dropdown menu.