Hi Aur0xx,
Welcome to the Apple Support Communities!
We understand that you are trying to add Hotmail and your work site to your Safari Top Sites, but when you clear the Safari history, these sites disappear.
The first article below explains that Top Sites that aren’t marked as permanent will be removed if you clear the Safari browsing history.
Safari for Mac: Clear your Safari browsing history
This next article explains how to keep a website in Top Sites.
View your Top Sites - Safari Help
Keep a website in Top Sites: Hold your pointer over the website’s thumbnail, then click the pin icon 
that appears. To unpin the website so other websites can replace it, click the pin icon again.
Once you have Hotmail and your work site set to permanently appear in Top Sites, resetting the Safari history shouldn't remove these sites.
Cheers!