Health visitor Dawn says...
Some parents may feel unhappy about the idea of bribing their child to use the potty, but rewards often help children do what we want them to do.
However, rewards work best when a child needs extra motivation to do something she's capable of, or almost ready to do. As your daughter was so successful initially, it's likely that she's just lost interest, so rewards may well help remotivate her. The reward needs to be small, as you'll be giving it frequently, so raisins or stickers work well.
Start by giving a reward for just sitting on the potty, then step it up to giving a reward when she actually produces something. Once toilet training is established, you may consider rewarding her to use the potty prior to a long journey, or when you know getting to a loo quickly may be difficult.