Once the interrupt is handled, reset the FIFOs (transmit/receive).The UARTLite core does not have any way to disabletheFIFOsfrom receiving data.
Consider using the following function at the end of the interrupt handler routine:
XUartLite_ResetFifos ( XUartLite * InstancePtr ) ;
This function is part of the Xilinx UARTLite software driver. Consult the driver documentation for more information.