All ministry should be bathed in prayer. Pray for your Sunday school and its growth. Pray that God gives you the wisdom and direction to take your Sunday school to the next level and be a prominent part of the community.

Survey past and present students. This may be done in conversation with young children, however, I believe for past and older students it is best to create a short survey.
Survey question should include:
1 What did/do you like about Sunday school?
2 What don't you like?
 

Search records for growth or shrinking attendance. If your church keeps records of your Sunday school attendance, put together a graph of your growth or shrinkage. This will be a good indicator of your Sunday schools ability to keep kids coming back.

Have a workers meeting. The Sunday school teachers will be a great resource of information on the Sunday school experience.
Some topics for discussion:
1. Evaluate the curriculum used; do the kids like it?
2. Evaluate your outreach programs and events.
3. Brainstorm new ideas.

 

Talk to parents. Try to get a feel for what kids are saying before and after church. Are they excited to go or not? Are they glad when it's over or do they keep talking of the fun stuff they did and learned.

Take a look at what other churches in your area are doing. While what works in one church doesn't always work in another, you may find things you can use or expand upon.

Set up a teachers meeting to present your findings and begin planning a new and improved program. Some people don't like change so don't be surprised if you face some opposition, but change is necessary if you want to get back on the path to growth. God expects us to do the work and he will provide the increase.