@Neil ******
You said ya got a Non-Imm-O visa. Now it is up to us to guess if you mean you still are on a 90-days single entry Non-imm-O visa, or if you already are on the 1-year Extension of Stay.
For BOTH you can buy a "single re-entry permit"
Which in the first case would keep the 90-days stay permit alive,
and in the second case would keep the extension alive for its whole duration.
However, a single re-entry permit for 1000.- THB (1200.- THB at the airports) would only be valid for ONE re-entry into Thailand