You may have a partner who can not come to the kitchen line quickly due to an impairment such as a sore knee. There are three ways you can help your partner.
If your partner is a beginning or intermediate player, s/he may not realize that one can often walk to the kitchen line after the return of serve or the third shot. If one starts out on that walk as soon as possible, being at the kitchen on time may not be a problem. So, simply tell your partner to start as soon as possible to walk to the kitchen line.
When returning a serve, return it high, even as high as a lob if necessary, giving your partner time to walk to the kitchen line. You may be surprised to discover that most good opponents cannot do anything better with a lobbed return that they wouldn’t be able to do with your fast and low return. In fact, some better players have more trouble dropping a lobbed return into the kitchen, than a lower shot, especially when playing outdoors in the wind. As always, you want your return-of-serve to go as far toward the back of the court as possible.
If your side is serving, you might consider returning a lob to the baseline instead of a dropshot, giving your partner more time to approach the kitchen.