Dont know about Rasberry leaf,never heard of that before.
It is possible to inject her with Galastop to induce a season but obviously it is a POM so you would have to take her to your vet for that.
However,when they have been artificially induced they are much harder to get into pup.
The other option is to move her to another kennel or to a friends house as quite often the change of environment is enough to cause them to break into season,even better if you could send her to someone who already has a bitch in season that usually does the trick.
Alternatively give the Rasberry leaf a go