You need to read RCREG to clear RCIF. I don't think you can clear it with pir1.5 = 0. If you don't clear RCIF you'll jump right back into the int handler each time you re-enable interrupts exiting your int handler.

Try something like this. Just change the LCD defines to match your LCD setup.
Code:
    DEFINE OSC 40                ' _HSPLL_OSC_1H & _HS_OSC_1H
	
	' // Setup for dev board LCD pinout
    DEFINE  LCD_DREG    PORTB 	 ' LCD I/O port
    DEFINE  LCD_DBIT    4        ' 4-bit data from RB4 to RB7
    DEFINE  LCD_RSREG   PORTB    ' Register select port
    DEFINE  LCD_RSBIT   2	    ' Register select pin
    DEFINE  LCD_EREG    PORTB    ' Enable port
    DEFINE  LCD_EBIT    3	    ' Enable pin
    DEFINE  LCD_BITS    4	    ' 4-bit data bus
    DEFINE  LCD_LINES   2        ' 2-line LCD
    DEFINE  LCD_COMANDUS 2000    ' LCD command delay
    DEFINE  LCD_DATAUS   50      ' LCD data delay	
	
    ' // Set USART parameters
    DEFINE  HSER_TXSTA  24h      ' Enable TXEN and BRGH=1
    DEFINE  HSER_RCSTA  90h      ' SPEN & CREN = 1
    DEFINE  HSER_SPBRG  129      ' SPBRG val for 19,200bps @40MHz    
    
    ' // Set USART interrupts, A/D, reg defs, etc,,
    SYMBOL RCIF = PIR1.5         ' Received character int flag
    INTCON = %11000000           ' enable global and Peripheral interrupt
    PIE1.5 = 1                   ' USART receive interrupt enabled
    ADCON1 = %00000111           ' Turn off A/D all digital

    X       VAR BYTE
    Teller  var byte
    
    pause 1000               ' LCD power-up / init time
    lcdout $FE,1              ' Clear screen / home cursor
    
    on interrupt GoTo handle ' Point to int handler
    
Main:
    lcdout $FE,1,dec teller  ' Print to LCD clearing previous char
    for X = 0 TO 50          ' Loop for 1 second
        pause 20
    next X
    goto Main

    Disable ' Interrupt handler
Handle:
    while RCIF         ' While RCIF is set, keep reading characters
     Teller = RCREG ' Reading character into Teller clears RCIF
    wend
    Resume
    Enable
    
    END
You may need to edit your default PBP 18F452.INC header file to make sure you're turning on HSPLL for 40MHz with a 10MHz crystal.

Commented out this line.
;__CONFIG _CONFIG1H, _OSCS_OFF_1H & _XT_OSC_1H
Add this below it, and save the file.
__CONFIG _CONFIG1H, _HSPLL_OSC_1H & _HS_OSC_1H