Knowing when to repair or replace your tub is important, and many factors should be taken into account to reach the appropriate conclusion.

-How old is your hot tub.

like any other product or appliance hot tubs have a service life, mid grade hot tubs 10-15 years, high end hot tubs as long as 20 years of life can be expected, after this point the tub can be re plumbed and parts replaced but one has to ask is this a cost effective rout, and in some situations it may be ie. tub is inside and cant be removed from home or cant be replaced.
another concern is the integrity of the hot tubs shell as eventually these wear out due to age and other factors such as uv light.

- Cost of repair vs replacement

In some cases especially with neglected and or frozen tubs the cost of the repairs needed may be close to the replacement value of your particular tub, research is important, and if this is the case replacement is almost certainly the better rout in some situations.

- peace of mind

Fixing an old tub that is in good shape and can be made reliable again is a good option and can be determined by an industry professional, while other tubs because of other factors such as proprietary parts or design that is incompatible with modern equipment, may not be able to be made reliable again, in this situation if a new tub isnt in the budget, some prolonging repairs may be able to be done, but we do not usually recommend rebuilding them as you will always be worried your old tubs going to break when its -40 on the first day of a holiday long weekend when no ones around to fix it, and all the money spent on the repairs was for not.