Can I revive an old streak after starting a new one?

Yes, as long as your new streak has not passed the old one.

Reviving joins the two streaks into one. If your old streak was 70 days and you have trained 4 days since it broke, reviving gives you 74.

So you can keep training while you decide. Every day you train in the meantime is added on top.

Once the new run is longer than the old one, the offer goes away. Reviving would make your streak smaller at that point, so there is nothing left to gain.

Learn more: My streak broke. Can I get it back?