If I understand your question correctly, you want to use a teleport entity to end a map, and then start a new map. If I get what you are saying, then i might be able to help. I have two possible solutions on mind.

1. you can use a teleport to send you to anew area of the map, or the so called "new map".

2. you can assign a trigger to an entity that tells the game to end the level. The trigger is 29. When creating the entity that you want to end the level with, it will lookf something like this:

/newent mapmodel N 29 T

where N is the mapmodel number, which is currently set to default to the default_map_models script in the data folder. 0 and up will render a mapmodel. while -1 will spawn an invisible trigger.
The variable T will set a tag number to the mapmodel, depending on what you set it to.
To set this up to end the level then load the next map your entity might look a little like this:

/newent mapmodel -1 29 T

And in the cfg file, you will need something like this:
alias level_trigger_T [sleep 3000 [map MAPNAME]]
Make sure the Ts match or else it wont work. this will tell the game to end the level, then 3 seconds later to load your next map. hope this helps a little!