We recommend that users save files every 5-10 minutes, and not to rely solely on the Terminal Server’s autosave feature.
By default, the Terminal Server’s Excel program has its autosave feature set at 10 minutes. If you close your Excel file without saving, the file will only have saved the most recent autosaved changes. These may not include changes you made since the last autosave.
To recover autosaved files, re-launch Excel, then go to File > Open. At the bottom of the panel, click on Recover Unsaved Workbooks, and this should show you your last autosaved files.