How to using JAL in RISCV in this example?

Question

Write a "replace" function that replaces every character in the source string between the first occurrence of character "(" and the first following ")" with character "?". This function should return the length of the string.

Example:
before: stop playing ("the lick") all the time!
after: stop playing (??????????) all the time!

return: 39*

What I wrote looks like this:

.data
input: .space 80
prompt: .asciz  "before:    "
msg1:   .asciz  "after:     "
msg2:   .asciz  "return: "

    .text
main:
    li  a7, 4
    la  a0, prompt
    ecall
    
    li  a7, 8
    la  a0, input
    li  a1, 80
    ecall

    li  t0, 40  # '('
    li  t1, 41  # ')'
    li  t2, 63  # *
    li  t3, 32  # space
    li  t4, 10  # \n
    li  t5, 0 #counter

loop1:  
    lbu a2, (a0)
    beq a2, t4, print #if string!=\n,go line exit and print
    beq a2, t0, loop2#if current char !=( go line 29 else go loop2:
    addi    t5, t5, 1 #add 1 to the counter
    jal a0
    #addi   a0, a0, 1 #move string to next char
    j   loop1
    
loop2:
    addi    t5, t5, 1 #add 1 to counter cuz '('
    addi    a0, a0, 1#move string to next char
    lbu a2, (a0) #give current a0 address to a2
    beq a2, t1, loop3 #if  != ')" go line 38 ,else go loop3:
    sb  t2, (a0) #store current t2 to a0's address
    j   loop2
    
loop3:
    addi    t5, t5, 1#add 1 to counter cuz ')'
    addi    a0, a0, 1#move string to next char
    lbu a2, (a0)
    beq a2, t4, print  #if current = '\n' go print
    j   loop3

print:  
    li  a7, 4
    la  a0, msg1
    ecall
        
    li  a7, 4
    la  a0, input
    ecall
    
    li  a7, 4
    la  a0, msg2
    ecall
        
    li  a7, 1
    add a0, t5, zero
    ecall
    
exit:   
    li  a7, 10
    ecall

But the teacher said that although it could complete the task in this way, it was not the correct process and that I needed to use 'jal' to do it. But I have no exposure to it, so please tell me what I should do.