There are lot of different factors:
- how big is payout
- payout is cash or ticket
- how the players at your table play
With 15 bb you don't have much space to see the flop, so it's basically a push or fold game.
If I have ~15 bb and I know that by folding all hands I will get a ticket, I get up from the computer and wait for the bubble to burst. Because then it doesn't matter if you finish 99th and win a ticket or if you fight for the final table.
If I see that I have loose players at the table, I wait for monsters (AA, KK, AK, QQ). If everyone folds, I try to raise in optimal circumstances, using my position and stealing blinds but no
bluffing too much. Every raise my bet, I fold (except monsters).
If I have 15 bb and I know that by folding all hands I will get a ticket, I check afk and wait for the bubble to burst. Because then it doesn't matter if you finish 99th and win a ticket or if you play for the final table. It doesn't matter.