1)You can use sugar instead of jaggery . But jaggery makes it so healthy and tasty than sugar.
2)You can add any flavouring in this like cocoa, vanilla, coconut.
3) You can add any nuts like you wish.
4)If your mixture gets cool and started to stuck in the bottom, just put it back on a low heat . The jaggery will melt again. Now form balls out of it.