Make white footprints to represent the path to eternal life. 
Ask the children to suggest things we need to do to return to Heavenly Father (such as be baptized and confirmed, pay tithing, and so on), and write these things on the footsteps. 
Place the footprints in a path and allow several children to walk along the path.  Add several dark-colored footprints that are labeled with things such as "drugs," "immodesty," and "dishonesty."  Place these footprints so that they veer off the path to eternal life.  Ask the children what a person can do to return to the path. 
Read D&C 58:42 and explain that we can repent and return when we are not on the correct path.  Help the children draw their own footprints.  Help them write, "Repentance help me return to Heavenly Father" on the footprint. 

Sing "Smiles" (CS 267), explaining that when we repent we exchange our frowning faces (sadness) for smiling faces (joy). 

Testify of the reality of repentance