Can you still level up your skills after a job advancement in maplestory?

I am an Evan in maplestory and i just leveled up to level 20 (2nd job advancement) but my first two skills weren’t leveled up yet! and when i leveled up again, i had no skill points for my first two skills, only the two new skills i got from my second job advancement. Does this mean i can’t level up my old skills anymore/!?!?!??! i really liked those please help!!!!!!!!!!! Thanks!!!!!!!!!!!!!!!!!!!!! <3