Use a heart-shaped cookie cutter to make their toast or their sandwich.
Tuck a love note into their backpack. Write a short note or draw a smiley face on a napkin and put it in their lunch box. Slide the note under their dinner plate or place it under their pillow.
Give your child coupons redeemable for things like a half hour of your undivided attention, their favorite dinner, playing a board game with them, etc. Send your child on a scavenger hunt around the house to find the coupons.