Having an issue generating interruption cycle in assembly language PLP

So far, I have been successfully generated an interruption after the first 200 cycles. However, I am not able to generate another interruption after the first one is being executed. I believe there is possibly something wrong with my return code. Helps or advice would be very appreciated. My goal is to generate an interruption every 200 cycles. Found this topic which is very helpful but it did not answer my question. PLP: Timer and Button Interrupt Service Routine

.org 0x10000000
li $sp, 0x10fffffc  # Stack pointer initialization
li $s0, sseg_lut    # Lookup table address used by sseg_display
lui $s1, 0xf070 # Interrupt controller register
lui $s2, 0xf0a0 # Seven segment display
# ****************************
# TODO: enable interrupts below
# ****************************
init:
li $a1, 0x00000000
li $a3, 0xf0200000 #memory of led
li $t2, 0b1011 #value used to enable the used interrupts
li $t4, 0b00000000 #value used to check if LEDs are off
li $t5, 0b11111111 #value used to check if LEDs are on
li $t6, 0xf0600000 #address of the Timer
li $t7, 0xffffffff
li $t8, 0xC8    #indicate 200 cycle
#Interrupt occurs every 200 cycle
subu $t7,$t7,$t8    
sw $t7,0($t6)
sw $t2, 0($s1) #set mask register to enable the used interrupts including Global Interrupt Enable 
li $iv, isr #interrupt vector 
###################
# NOTE: Do not add or modify any code within this main loop
main:
jal sseg_display
    nop
    addiu $a0, $a0, 1
    j main
    nop
# ****************************************
# TODO: add interrupt service routine below
# ****************************************
isr: 
        lw $i0, 0($t8) #check what is stored currently on LEDs
        lw $i1, 4($s1) #load what value is in the status register
    #li $i0, 0xf0700000
    #lw $i1, 4($i0)     # read the status register
            beq $t4, $i0, on #if led off then on
            nop
            bne $t4, $i0, off #if led on then off
            nop
            on:
        addu $t7, $t7, $t8 #calculate input for led on
                    sw $t7, 0($a3) #turn on the led
        li $i1, 0
                    j end
                    nop
            off:
        li $t7, 0
                    sw $t7, 0($a3) #turn off the led
        li $i1, 0
                    j end
                    nop
    end:
    #return from interrupt, set Global Interrupt Enable bit in delay slot of returning jump instruction
    sw $i1, 4($i0)     # clear any handled interrupts in the status register
    lw $i1, 0($i0)     # get the mask register
    ori $i1, $i1, 0
    jr $ir
    sw $i1, 0($s1)     # store the mask register in the delay slot to guarantee proper exit