1.) Add in fiber to the diet. This can be carrots, canned green beans, metamucil wafers (the cinnamon apple are typically a favorite), reducing the dry food and adding white rice (1/2 cup per meal), and/ or 1 tbsp of canned pumpkin twice daily. The purpose of the fiber is to increase the bulk of the meal which stimulates stomach
emptying and increases gi motility
2.) Elevate food/ water bowls to chest level.
3.) No other changes to breakfast since there is no regurgitation in the mornings
4.) Dinner is now in two parts. 1/2 at the regular time you are currently feeding and the other half about 2-3 hours later, before bed. In between the feedings at about an hour after the first afternoon meal please take on a walk. This is an active walk not a leisurely walk of at least 15 minutes ideally 30+. Walks are very important increasing motility of the gi tract and increases stomach emptying as well. Since we are regurgitating this means that the food is in the stomach longer than it should be and we need to take efforts to empty the stomach to reduce this risk.
5.) Begin pepcid 10 mg every 12 hours (preferably 10-15 minutes prior to meals) OR prilosec 20 mg daily about 15 minutes before dinner based on the weight you gave me...
If there is still regurgitation at this point then unfortunately the issue maybe more mechanical and she may need x-rays and bloodwork to determine the underlying cause. If it is due to the issues I commonly see in pets at this age and not medical in origin this should be effective in reducing her signs.
Please let me know if this information makes sense and any additional questions I can assist with this evening!