Welcome to the forum. Lifting bridges are not uncommon on any older, 12 string guitars. The simple extra stress of six more strings does create problems with neck sets, lifting bridges, bracing, etc.. The good news is a bridge re-glue is a very simple thing to do. The old bridge is removed, usually via the application of heat and the careful use of a putty knife. Once the bridge is off, the surfaces are sanded clean, glue applied and the bridge is clamped back in place. After the clamps are released, usually 12-24 hours, then it's a simple matter of cleaning out the bridge pin holes, string her up and you're ready to go. Should not cost more than $50, assuming no other issues need to be addressed.