Vienna to Budapest is a simple 2h50 ride.
Budapest to Prague is about a 7h ride
Vienna to Bled-Jezero is ~7 hrs, while Budapest-Bled-Jezero is about 11 hrs.
Vienna - Ljubljana is about 6 hrs.
I would skip either Budapest or Lake Bled and spend more time in other locations.
Another option is to go from Bled to Venice (5 hrs) and fly from there to PRG.... there's at least one LCC that does that route. If this is before 30 SEP, WizzAir actually flies out of Marco Polo, not out of Treviso, which should make things even simpler.