How do I get older streps to bloom again?

I have older streps which are growing very well but not producing flowers; any suggestions on how to prompt them into blooming?

As I understand, streps have a given number of blooms per leaf, so once the quota has been bloomed out, you have to wait until new leaves are blooming size. Of course, if the mix is old, this might be a good time to refresh it.

Keyring doesn't know it but I needed this answer...thanks

Thanks from me also! I have a couple of Strep's given me in trades and don't know much about them!