AT89c51RE2 replaced with AT89LP51RD2, ISP programming
The AT89C series ISP takes place over UART and uses Flip or BatchISP to program. The AT89LP series ISP takes place over SPI. See this app note for programming the AT89LP series.

There is a whole different line of tools for those chips available. Have a look at AT89LP ISP Studio instead. Or possibly AT89LP Developer Studio.

I found the following note on terminology used for this series of chips in the datasheet (page189):


  Note: In this document the term Bootloader, or BOOT,
  is used to when referring to the UART-based ROM bootloader
  and In-System Programming, or ISP, is used with
  reference to the SPI-based interface. This is different
  from AT89C51RD2/ED2/ID2 where ISP also referred to the
  bootloader (as no SPI programming interface was present).
  However, it should be noted that both interfaces are
  perfectly capable of performing in-system programming,
  i.e programming the device when it is already mounted
  in the final end-user system.


Flip (and presumably BatchISP) can be used when accessing the Bootloader through the UART. But AT89LP ISP Studio must be used when programming through the SPI.