From what you say, the bitch had one pup last time?

If this is right then it is very unlikely that the present pregnancy will be any better.

Bitches are designed for a multiple birth. The pups inside her give the hormones to the bloodstream of the dam that initiate whelping. So, no puppies, no whelp.
With one pup it is highly unlikely that enough hormone is released to get things going.
Another problem with only one pup is that it tends to grow too big to birth normally even if the hormone load is good.
The next thing to think about is why there was just one pup?
Even as a first time bitch this is not normal and perhaps you should do the decent thing and opt for speying rather than further pregnancies.