If I make payments on a TV through a rental store but it is not always on time, but it is always paid,can they repo my television?

No, most of the rent to own stores can come get it if it is one day outside of the acceptable pay period ( grace) most allow so many days ( about a week) for you to pay with a late fee.

Now on the other hand, most don't want a used TV or sofa or anything back, so if they think they can just make you pay a lot of late fees, they are even happier, since they are making about double on the same sale.