Point in time recovery + replication

Hello Everyone,

I have a primary / hot standby scenario with streaming replication.
Postgres version is 9.1.8.

A full backup is made nightly on the primary and copied to the secondary,
just for backup purposes, the replication is never stopped /restarted.

Supose that for a reason I need to restore the primary to a point in time,
let's say just after the last backup. I've done this by:

1) stoping de databese
2)restoring the backup
3) creatng a recovery.conf where I specified a recovery_target accordingly
4) start the database

This works fine on the primary. The quesion is how do I restart the
replication on the secondary, on the new timeline?

I tried to restore the same backup on the secondary and starting
the continuous recovery, but it starts on the previous timeline.
I also tried to set the recovery_target_timeline in the secondary to the
new timeline, but I get an error. Do I need to get a new copy of the
primary to continue the replication?