Good job and keep it up you are following the steps of our Honorable PM and our country's father you'll surely get success in that.
The suggestions that I can put forward are;
(i) First of all don't be rude towards children and dont feel shy in cleaning by yourself because if you'll do so then children would feel happy to help or else they wont pay any respect to you.
(ii) You can give a speech regarding this.
(iii) You can give awards to children for their performance in cleaning.
I think that would do try it...