Whether it's on favourite player's replica or on a real one that sees a lot of time on the gridiron, the iron-on lettering on a football jersey will begin to peel up after many washings. Instead of peeling the letters off completely or wearing a ratty-looking jersey, you can use hem tape to reattach the letters. Hem tape, also known as fusible webbing, is available at most fabric stores. It is a no-sew way to fix many pieces of fabric.
Cut a piece of hem tape large enough to fit exactly under the letter that is peeling up. None should be sticking out from under the letter.
Place a thin towel over the letter you are fixing. A pillowcase also works.
Iron over the area on medium-high heat, moving the iron constantly, for 30 seconds to 1 minute.
Remove the towel and check to see that the letter is firmly attached. If not, iron for an additional 30 seconds.
Repeat for each letter that is beginning to peel up. Wash as usual.
Some brands of fusible webbing come in sheets.
Do not iron directly on the letters or you might melt them.