My voting power used to be very low that I couldn't vote anymore. I have been trying to replenish my voting power, but it takes time. From what I understand, you can get 20% voting power back per day.
The hard thing is that I like upvoting all the good content that I see. Until I get back to near 100% I'm using the app on my phone to let me use the voting slider. I will probably get near 100% in about 4 days from now. Until them I am trying my best to still upvote all the good quality content I find here.