Remove Holes Existing Within a Single Polygon for a specific area in Qgis

1) create polygons where you have a hole. This can be done with the "difference" tool (just manually draw a large polygon in another layer, or do it with the buffer tool).

2) select the polygons which are less than 200m² and merge those with your original shapefile (you can use the union tool).

3) use the dissolve tool to revert to a single polygon

Googling a bit I came to know this "ringer" experimental plugin for qgis, which seems to be good for your task. If this works (I did not test it), this would let you convert your holes into polygons. Then you would create a new field in the attribute table of the new polygons and calculate their area (with the field calculator). Then you would merge the hole polygons with your original polygon, selecting only those holes which are larger than 200m2. Hope this helps.

1) Polygons to lines

2) Lines to polygons

3) Dissolve

4) Select polygons from point 2) < 200 m2

5) Difference polygons from point 3) with polygons from point 4)