Lee, the engines all have different schedules for refreshing their index. Furthermore most engines treat sites differently, depending on factors like backlinks, freshness, CTR.
Basically you can not do much to enforce refreshment as long as you don't pay, i.e. use a PFI programme.
Getting pages from a site, which is already indexed, into a PFI programme, is not absolutely riskfree. Several people have reported that upon joining a PFI program with some pages has lead to (temporary) drops of the free pages previously indexed.
In short: I would recommend to just wait for the natural refreshment cycles of the engines.