The centre-back initially joined the National League side on a four-week deal last month.
However, having made seven appearances for the Cards since then, all parties have now agreed for the 19-year-old to remain at Park View Road until Saturday, January 2.
Thomas has been named in Charlton's matchday squad on five occasions, although he is yet to make his senior debut for the Championship club.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | Wycombe WanderersWycombe | 14 | 10 | 2 | 2 | 32 | 16 | 16 | 32 |
| 2 | Birmingham CityBirmingham | 13 | 9 | 3 | 1 | 24 | 12 | 12 | 30 |
| 3 | Wrexham | 14 | 8 | 4 | 2 | 22 | 10 | 12 | 28 |
| 4 | Barnsley | 14 | 7 | 4 | 3 | 23 | 18 | 5 | 25 |
| 5 | Lincoln CityLincoln | 14 | 7 | 4 | 3 | 21 | 17 | 4 | 25 |
| 6 | Stockport CountyStockport | 15 | 6 | 6 | 3 | 25 | 17 | 8 | 24 |
| 7 | Mansfield TownMansfield | 13 | 7 | 3 | 3 | 20 | 15 | 5 | 24 |
| 8 | Huddersfield TownHuddersfield | 14 | 7 | 2 | 5 | 21 | 14 | 7 | 23 |
| 9 | Reading | 14 | 7 | 2 | 5 | 22 | 21 | 1 | 23 |
| 10 | Bolton WanderersBolton | 14 | 7 | 2 | 5 | 22 | 24 | -2 | 23 |
| 11 | Exeter CityExeter | 13 | 7 | 1 | 5 | 14 | 10 | 4 | 22 |
| 12 | Peterborough UnitedPeterborough | 15 | 6 | 3 | 6 | 31 | 27 | 4 | 21 |
| 13 | Charlton AthleticCharlton | 14 | 5 | 4 | 5 | 15 | 15 | 0 | 19 |
| 14 | Stevenage | 15 | 5 | 3 | 7 | 11 | 16 | -5 | 18 |
| 15 | Rotherham UnitedRotherham | 15 | 4 | 5 | 6 | 14 | 18 | -4 | 17 |
| 16 | Bristol Rovers | 14 | 5 | 2 | 7 | 16 | 21 | -5 | 17 |
| 17 | Northampton TownNorthampton | 14 | 4 | 4 | 6 | 18 | 21 | -3 | 16 |
| 18 | Blackpool | 14 | 4 | 4 | 6 | 21 | 28 | -7 | 16 |
| 19 | Wigan AthleticWigan | 14 | 3 | 5 | 6 | 12 | 12 | 0 | 14 |
| 20 | Leyton Orient | 14 | 4 | 2 | 8 | 14 | 18 | -4 | 14 |
| 21 | Crawley TownCrawley | 15 | 3 | 3 | 9 | 14 | 27 | -13 | 12 |
| 22 | Cambridge UnitedCambridge | 13 | 3 | 1 | 9 | 12 | 23 | -11 | 10 |
| 23 | Burton Albion | 14 | 1 | 5 | 8 | 15 | 25 | -10 | 8 |
| 24 | Shrewsbury TownShrewsbury | 15 | 2 | 2 | 11 | 13 | 27 | -14 | 8 |
| > League One Full Table | |||||||||
