Bentley i-model Composition Server Processors Increase


i have an existing i-model server installed as Standart  (SS4 590 on windows 2008 r2)

How can i increase numbers of processors and especially Iplot Processors  (as i can configure with custom install) on my existing environment without reinstalling the server ?

I have issues when one document is stuck in "rendition" then all other PDF conversions are waiting in job monitor.

best regards