There are rumors that her label is choosing between Lets Dance and Never Undersetimate A Girl as the third single.
And I also heard that her label might send Lets Dance to mainstream radio and mtv while Never Underestimate A Girl will go to radio disney and disney channel. I guess they wanna increase the album sales by putting out 2 different singles for 2 different markets.
But these are all just rumors, besides is Say OK flops than I doubt they'll be another single.
If the choice is between Never Underestimate A Girl and Let's Dance, she MUST release NUAG. Its OK if she releases 2 different singles at one time, but I still do think Let's Dance wouldnt do that good.