It's probably not worth it. (I assume you are talking about placing linoleum pre-glued tiles over the old linoleum). 7 years is quite a few miles on linoleum flooring...I'd hate for you to go to the expense of putting down new tiles just to have the old linoleum start to come unglued on you and wreck the new job...but if it's not a lot of square footage to cover it wouldn't hurt. I say this because if it's a small area it won't make much difference relative to a lot of cost.