I reccomand taping them up for about 10 days, take it of then for a few days and if they are not up then tape it for 10 days again.
If they don't come up then they are just dont coming up.
Take the gray paper thing from a toiletpaperroll, cut it like the ears are shaped and so it fits perfect in the ears, than tape it too the ear.
It's more likely that they get up if you do that
Mine has floppy ears but i love him not any less for that!
He's just cute with his litle floppy ears