How can I renovate a tired passion flower?

It grows in a pot in my south facing conservatory in Manchester, where it has been for maybe 4 or 5 years now. All I've done in that time is fed, watered and removed dead leaves and branches. It flowered just once - in 2007 - and now is very leggy with very few leaves. It has grown to maybe 5m from the base to the extremes.

Can it be renovated - if so what should I do?

Or am I better just replacing it?

Thanks!