Most tenancy agreements (well all 10 i've ever had!) have clauses in that state the tenant must keep the proprty in good order. They also usually allow for a periodic inspection by the landlord. The period between inspection varies. one of mine said every 3 months, another said every 6 months. Fortunately none of my landlords have seen fit to take up their rights on this, but then, i keep my places as i found them.
If your tenancy agreement with your tenant allows for it, then you could agree a visiting schedule giving her plenty of notice you are coming.
Whilst you cant force her hand into keeping the place up, it is better you know in advance if things are sliding further, so you can try and resolve it sooner. The "leave them and fix it when they move out" point of view may be true, but some damage needs catching before this, and you dont want it to require more than can be paid for with the deposit, when they have done a runner!