Question about Retrieve Filter in SPI Framework

Hello Experts,

I'm facing an issue about retrieve filter in SPI Framework, when I call retrieve method of SPI twice with same ID, the 2nd call will get nothing, I resaerch a lot and found the reason from wiki page SPI, the reason is

1. The Application Model will always evaluate the side-effect and the node invalidation of the called Service Provider (SP) operations and clear the buffer of already retrieved node IDs accordingly.
   After a CLEAN_UP call all buffers of already retrieved node IDs will be cleared.
   This means that after a node got invalidated via one of those mechanisms, the RETRIEVE will reach the SP again to fetch the up to date data.
   Example:
   You call the RETRIEVE with ID '1' of node A twice, the first time the call will reach the SP, the second time the SP will not get called. Now you call an ACTION which invalidates node A and afterwards you call again the RETRIEVE with ID '1' of node A. Now the RETRIEVE will reach the SP again.

My question is how to make a node invalidated or how to clear the buffer of already retrieved node IDs by abap code?

thank you in advanced,

best regards,

felix