The 9 previous yanks are saved in registers called `1` through `9`. You can recall the next-to-last yank with `"1p`, the previous one with `"2p` and so on. The command `:reg` shows the registers that are available for pasting.
If you want a yank to last longer, use a letter register.
For the more obscure yank-related commands, start reading at `:help "` in the manual.