I am moving my hot tub to my new house and I dont have a empy spot in electric box for anymore breakers and its a 100 amp box they say I need to upgrade to a 200 amp box for about 1,500-2,000 any suggestions???

100 amps is a small box. The only alternative to replacing would be to use a gas heater for the spa, which will run you about the same amount and you'd still have a maxed out breaker panel. I'd do the upgrade.