Below are some options to help locate these signals:
1) Use KEEP_HIERARCHY to maintain the hierarchy structure of the final netlist so that finding signals are easier.
2) Apply KEEP attributes to the signals you wish to see in the simulation. This ensures that they are not trimmed during the optimization processes of XST or PAR.
3) Check within the UUT level. In a post-route simulation, most signals are contained within the UUT level, with hierarchy separators to define each signal.